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UNIVERSITY OF CALIFORNIA. 


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The D. Van Nostrand Company 
intend this book to be sold to the Public 
at the advertised price, and supply it to 
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of reduction. 











CHEMICAL REAGENTS 


THEIR 


PURITY AND TESTS 


A .NEW AND IMPROVED TEXT 
BASED ON AND REPLACING THE LATEST EDITION OF 


KRAUCH’S 


“DIE PRUFUNG DER CHEMISCHEN REAGENTIEN AUF REINHEIT ” 


BY 


E. MERCK 


AUTHORIZED TRANSLATION 


BY 


HENRY SCHENCK, A.B. (Harvarp) 










Ci BRAR: 
OF THE 


| UNIVERSITY 
OF 


\. 










> 
= 


CALIFORNIA 





NEW YORK 


D. VAN NOSTRAND COMPANY 


23 MURRAY AND 27 WARREN Sts. 


1907 


CAB a? 
M42 


Copyright, 1907 
By D. Van Nostranp CoMpANY 


GENERAL 


The Plimpton Press Norwood Mass. U.S.A. 


DR. KRAUCH’S PREFACE 


As long ago as the early seventies I felt the need of a 
treatise on Chemical Reagents, and thought of compiling 
such a work. I was then an assistant in the chemical 
laboratory -of the Government Agricultural Experiment 
Station at Munster, and in my chemical work there met with 
constant difficulties on account of the great variations in 
the chemicals which were graded as “‘C. P.” “puriss,’’ ete. 
It was my aim to fix uniform standards for such chemicals — 
as are used in analytical work, such standards to define 
closely the degree of purity of the chemicals and yet to be 
possible of attainment in practice by the manufacturer. 

Not until 1888, however, did my work in this direction 
take the tangible form of a book, ‘‘ Die Pruejung der Chemai- 
schen Reagentien auf Reinheit.’ A second revised and 
enlarged edition was published in 1891. In 1896 a third 
edition, carefully revised and still further enlarged, was pub- 
lished. Since that time a good many changes have taken 
place, so that my book again needed revision. As I was 
unable t6 undertake this work, Mr. E. Merck, appreciating 
the usefulness of such a work'as mine, published in 1905 
what might be considered its up-to-date revision. 

It is a source of gratification to me to see this work trans- 
lated and placed before my colleagues across the sea. Such 
changes and additions as the translator has made in order 
to adapt the book to their particular needs, have my approval. 

Darmstadt, February, 1907. 
Dr, C. Kraucu. 


iil 


192831 


a 


fied 





-TRANSLATOR’S PREFACE 


Tue desire of American chemists to rid themselves of the _ 
misleading term ‘“‘C.P.,’’ and to get in its stead definite state- 
ments as to the exact degree of purity of their reagents or 
the exact limit of the impurities, impelled the American 
Chemical Society, in 1902, to create a Committee on Purity 
of Reagents. In 1906 this Committee advised against the 
publication of a book, because — to use their own language 
— ‘‘ until further work is done and more data collected, such 
a work would be practically only a duplicate of the work of 
Krauch.”’ * 

It is evident that the work of the Committee is being per- 
formed with most painstaking care, as, at the time of the last 
report, the Committee was working on “ perfecting a method 
for the accurate colorimetric determination of traces of iron.’’* 
It is evident, too, that if the collection of data regarding other 
tests than those for iron is pursued with the same painstaking 
care, the complete report of the Committee will not be ready 
for publication for several years. My excuse for present- 
ing this translation now lies, therefore, in the hope that, until 
the work of the Committee appears, chemists will generally 
make acceptance of their purchases conditional upon their 
coming up to the specifications of purity prescribed by this 
translation. 

The additions mentioned by Dr. Krauch, in the preface 
he has kindly consented to write for this book, are limited to 

* See Journal of the American Chemical Society, Vol. XXVIII, No. 8, 


pp. 61 and 62. 
Vv 


vi TRANSLATOR’S PREFACE 


articles which are universally used here but do not seem to be 
so in Europe, and for which specifications could be found 
in authoritative American publications. They are Glacial 
Acetic Acid 99.5%, 36% Acetic Acid, Hydrochloric Acid of 
a specific gravity of 1.050, Nitric Acid with one of 1.40, 
Phosphoric Acid with one of 1.057, 10% Sulphuric Acid, 
28% Ammonia Water, 95% Alcohol, and Glycerin of a 1.250 
specific gravity. The slight changes obviously necessary in 
the text on account of these additions have been carefully 
made. 
THE TRANSLATOR. 


TRANSLATOR’S NOTE 


For the sake of brevity, expressions throughout the book 
are sometimes used without full qualification. The follow- 
ing is then to be their interpretation. | 

Atomic Weights, Quantitative Calulations, etc., are based 
on the table of International Atomic Weights for 1906 
in which O = 16. 

Specific Gravities are given at + 15°C, compared with 
water at + 4°C. 

Unweighable Residue or words to that effect apply to 
residues weighing 0.0005 gm. or less. 

Solutions of chemicals to be tested are made from 1 gm. 
diluted to 20 ce. or proportionately. 

Volumetric Determinations can of course be made with 
other solutions than the potassium hydroxide and hydro- 
chloric acid solutions generally selected, provided they be 
equivalent. In such substitution, however, due regard must 
be given to the suitableness of the indicator. 

Nitric Acid has a specific gravity of 1.153. 

Hydrochloric Acid, one of 1.124. 

Ammonia Water, that of 0.96. 

_ The Marsh Apparatus should be set up with a 200 ce. 
generating flask. 

The tests presuppose the use of Jena or some equally re- 
sistant Glassware. 


{f 














ZEBRARYE 

: ¥ OF THE 
UNIVERSITY 
OF ; 


S.CALIFORWEA 






CHEMICAL REAGENTS 


ACETONE 
(CHs),CO. Mol. Wt. 58.04. 


A clear, colorless liquid, boiling at 56 to 57° C., with a 
specific gravity of 0.797. 


TESTS OF PURITY 


Residue on Evaporation. — 25 cc. of acetone on evaporation 
should leave no weighable residue. 

Acids. — Acetone should not redden blue litmus paper. 

Solubility in Water. — Acetone should be miscible with an 
equal volume of water, yielding a clear liquid. | 

Aldehydes. — On heating 10 cc. of acetone with 5 cc. of 
ammoniacal silver nitrate solution for fifteen minutes on a 
steam-bath, the mixture must not acquire a brown color. 

Substances Oxidizable by Permanganate. — On adding one 
drop of a 1:1000 solution of potassium permanganate to 
10 cc. of acetone, and maintaining a temperature of 15° C., 
the pink color should not be entirely discharged within fifteen 
minutes. 

Water. — On mixing equal volumes of acetone and petro- 
leum benzin (boiling-point 40° to 70° C.), two layers should 
not be formed. 


Norr. — Regarding the quantitative determination of acetone, see 
G. Lunge, Chem.-tech. Untersuch.-Meth., 4 ed., 8, 653 (1900). G. Kra- 
mer, Ber., 18, 1000 (1880); J. Chem. Soc., 38, 826 (1880). J. Messinger, 
Ber., 21, 3366 (1888); J. Chem. Soc., 56, 313 (1889). H. Strache, Mo- 
natsh. Chem., 12, 524 (1891) [or Ztschr. anal. Chem., 31, 573 (1892)]; 
J. Chem. Soc., 62, 546 (1892). F. Robineau and G. Rollin, Ztschr. anal. 
Chem., 83, 87 (1894); J. Chem. Soc., 64, II, 556 (1893). 

1 


2 CHEMICAL REAGENTS 


ACID ACETIC 
HC:H302. Mol. Wt. 60.03. 


I 


ACID ACETIC, 99.5% 


A clear, colorless liquid, with a strong odor; miscible in all 
proportions with water or alcohol, and containing at least 
99.5 per cent of HC,H,O,. Specific gravity about 1.048 at 
25° C. At about + 15.65° C. it solidifies. 


TESTS OF PURITY 

Non-volatile Matter. — 10 cc. of acetic acid should leave 
no weighable residue on evaporation. 

Hydrochloric Acid. — 5 cc. of acetic acid diluted with 50 ce. 
of water should afford no turbidity on the addition of 5 cc. of 
nitric acid followed by silver nitrate solution. 

Sulphuric Acid. — On boiling a mixture of 10 cc. of acetic 
acid and 150 ec. of water, and then adding barium chloride 
solution, no precipitate of barium sulphate should form on 
standing twelve hours. 

Heavy Metals and Earths. — 

(a) A mixture of 20 cc. of acetic acid and 100 ec. of water 
should not be affected by passing through it a current 
of hydrogen sulphide gas. ; 

(6) On diluting 10 ce. of acetic acid with 100 cc. of water 
and adding an excess of ammonia water, no green 
color should be developed on the addition of am- 
monium sulphide solution; nor should a turbidity 
or precipitate form on adding ammonium oxalate 
solution. | 

Formic and Sulphurous Acids. — 2 cc. of the acid are 
supersaturated with 8 to 10 cc. of ammonia water and a 
little silver nitrate solution added. No dark deposit should 
occur on boiling two minutes. 


CHEMICAL REAGENTS 3 


Substances Reducing Permanganate.— 2 cc. of the acid 
are diluted with 10 ec. of water, and 0.1 cc. of decinormal 
solution of potassium permanganate added. The pink 
color should not be entirely changed to brown within two 
hours. 

Other Empyreumatic Bodies. — No smoky odor should be 
- noticeable upon making 10 cc. of the acid alkaline with solu- 
tion of potassium hydroxide. 

Quantitative Determinations. — Dilute 10 gm. of acetic acid 
with sufficient water to make 100 cc. Titrate 10 cc. of this 
solution with normal potassium hydroxide solution, using 
phenolphthalein as the indicator. 

1 ec. of normal KOH = 0.06003 gm. HC,H,0O.,, log. 77837. 

The acetic acid content may also be ascertained from the 
specific gravity, if due note be taken of the fact that the 
specific gravities above 1.0553 represent in each case two 
liquids of different acetic acid content.* 


II 
ACID ACETIC, GLACIAL, 96% 


A clear, colorless liquid with a pungent odor, solidifying 
at about + 10° C.; specific gravity 1.064, and boiling point 
117 to 118° C. It contains at least 96 per cent of HC,H,O,. 


TESTS OF PURITY 


This acid should respond to the tests for non-volatile 
matter, hydrochloric acid, sulphuric acid, heavy metals, and 
quantitative determinations, as described under Acid Acetic 
99.5 per cent. Its strength, however, is less. The following 
test also applies. : 

Substances Reducing Permanganate. — On adding 0.3 ce. 


* Compare G. Lunge, Chem.-tech. Untersuch.-Meth., 4 ed., 3, 681 (1900). 
Also U. S. Pharmacopeeia, VIII, p. 610 (1905). 


+ CHEMICAL REAGENTS 


of decinormal potassium permanganate solution to a mixture 
of 5 ec. of acetic acid with 15 ce. of water, the red color 
should not disappear within fifteen minutes. 


III 
ACID ACETIC, 90% 
A colorless liquid having a specific gravity 1.071 and 
containing at least 90 per cent of HC,H,0O,. 
TESTS OF PURITY 


The tests to be made are those given under Acid Acetic, 
Glacial, 96 per cent, observing the conditions there described. 


IV 
ACID ACETIC, 36% 
A clear, colorless liquid, specific gravity about 1.048, and 
containing about 36 per cent of HC,H,0O,. 
TESTS OF PURITY 


The tests of purity and details of execution are the same 
as those given under Acid Acetic, Glacial, 96 per cent. But 
instead of 10 gm. (or cc.) of 96 per cent, use 25 gm. (or cc.) 
of the 36 per cent acid. 


z 
ACID ACETIC, DILUTED, 30% 


A colorless liquid having the specific gravity 1.041. The 
liquid contains about 30 per cent of HC,H,0O.,. 


TESTS OF PURITY 
The tests to be made are those given under Acid Acetic, 
Glacial, 96 per cent, observing the conditions there described. 
But instead of 10 gm. of the 96 per cent, use 30 gm. of the 
30 per cent. 


CHEMICAL REAGENTS 5 


(ACID) ACETIC ANHYDRIDE 
(CH3:CO)20. Mol. Wt. 102.05. 


A colorless liquid of pungent odor, boiling at 137° C. 
Specific gravity 1.08. 

On pouring acetic anhydride into water, it does not at 
first mix with the latter, but sinks to the bottom of the 
vessel. Gradually, however, it dissolves, forming acetic acid. 


TESTS OF PURITY 


Hydrochloric Acid. — 1 cc. of acetic anhydride diluted with 
50 ec. of water, and acidulated with 5 cc. of nitric acid, should 
give no reaction with silver nitrate solution. 

Non-volatile Matter. — 10 cc. of acetic anhydride should 
leave no weighable residue on evaporation. 

Quantitative Determination. — Dissolve 10 gm. of acetic 
anhydride in water and dilute to 100 cc. Titrate 10 ce. of 
this solution with normal potassium hydroxide solution, using 
phenolphthalein as indicator. It should require at least 
19.3. cc. of the normal potassium hydroxide solution to 
develop the pink color. 

1 cc. of normal KOH = 0.051025 gm. of (CH,’CO),O, log. 
70777. 

(ACID) BORIC ANHYDRIDE 
(Boron TrioxipE; Boric Acip, FusEp) 
: B.Os. Mol. Wt. 70.0. 

Brittle, vitreous, hygroscopic lumps used in silicate analy- 
sis, according to Jannasch.* 

TESTS OF PURITY 


Silica, Alkalies, etc. — Add 50 cc. of methyl alcohol-hydro- 


* References : P. Jannasch and O. Heidenreich, Ztschr. anorgan. Chem., 
12, 211 (1896) [or Ztschr. anal. Chem., 36, 382 (1897)]; J. Chem. Soc., 
70, II, 576 (1896). 


6 CHEMICAL REAGENTS 


chloric acid * to 5 gm. of the powdered boric anhydride in a 
weighed platinum dish, stir with a platinum wire until com- 
pletely dissolved, and evaporate the liquid over a small flame, 
the platinum dish being placed on wire gauze. If a residue 
remains, it is treated anew with 25 cc. of the methyl! alcohol- 
hydrochloric acid, the liquid evaporated, and the dish and 
contents gently ignited. There must remain no weighable 
residue. 


ACID CARMINIC + 
C22H220i3 


Purple-brown, amorphous masses, affording a dark red 
powder on trituration. Carminic acid is easily soluble in 
water and in alcohol, but is insoluble in benzene and chloro- 
form. It has no constant melting-point. 


TESTS OF PURITY 


Solubility. —1 gm. of carminic acid dissolves completely 
in 2 ec. of water. The addition of 20 cc. of 90 per cent 
alcohol to this solution should cause no appreciable precipi- 
tation. 


* The methyl alcohol-hydrochloric acid is prepared by saturating pure, 
anhydrous methyl alcohol, keeping the temperature low, with thoroughly 
dried hydrochloric acid gas. On standing for some time, however, the 
methyl alcohol-hydrochloric acid loses its. original effectiveness. 

+ References : E. Schunck and L. Marchlewski, Ber., 27, 2979 (1894); 
J. Chem. Soc., 68, I, 67 (1895). C. Liebermann and H. Voswinckel, 
Ber., 30, 688 (1897); J. Chem. Soc., 72, I, 292 (1897). Ber., 30, 1731 
(1897); J. Chem. Soc., 72, I, 539 (1897). C. Liebermann, P. Horing, and 
F. Wiedemann, Ber., 33, 149 (1900); J. Chem. Soc., 78, I, 236 (1900). 
J. Landau, Ber., 38, 2446 (1900); J. Chem. Soc., 78, I, 661 (1900). C. 
Liebermann and J. Landau, Ber., 34, 2153 (1901); J. Chem. Soc., 80, I, 
545 (1901). C. Liebermann and S. Lindenbaum, Ber., 35, 2910 (1902); 
J. Chem. Soc., 82, I, 787 (1902). 

Regarding the use of carminic acid as a reagent see T. J. Bogolomow 
and N. J. Wassilieff, Pharm. Centrhl., 40, 120 (1899); E. Merck, Annual 
Report (on year 1898). 


CHEMICAL REAGENTS 7 


If the carminic acid is intended to be used as an indicator 
in acidimetry, it must first be tested as to its sensitiveness, 
as follows: 

Dissolve 1 gm. of the carminic acid in 100 cc. of water 
and add one drop of this solution to a solution of 5 gm. of 
ammonium chloride in 50 cc. of water. The addition to this 
latter solution of one drop of decinormal potassium hydroxide 
solution should cause a change in color from yellowish-red 
to violet-red. 


ACID CITRIC 
CeH;O07 + H.O. Mol. Wt. 210.08. 


Colorless, odorless, rhombic prisms, efflorescing superficially 
in warm air. , 

Citric acid is soluble in 0.75 part of cold and in 0.5 part of 
boiling water; in 1 part of 85 per cent alcohol, and in 50 
parts of ether. 


TESTS OF PURITY 

Oxalic and Tartaric * Acids. — On dissolving 1 gm. of citric 
acid in 2 cc. of water, and adding 10 drops of a 1:2 potas- 
sium acetate solution and 5 cc. of alcohol 85 per cent, no 
turbidity should be produced, nor should a crystalline deposit 
form within two hours. 

Tartaric Acid and Sugar. — 1 gm. of citric acid and 10 cc. 
of sulphuric acid are ground together in a porcelain mortar 
previously rinsed with sulphuric acid. When this mixture 
is then heated in a test tube for an hour in a boiling water- 
bath it acquires at most a slight yellow color, but no brown 
color should develop. | 

Sulphuric Acid. — 20 cc. of the 1:10 aqueous solution must 

* Regarding the detection of tartaric acid in citric acid see Merck’s 


Reagentien-Verzeichnis (1903), p. 170; A. I. Cohn, Tests and Reagents 
(1903), pp. 40, 51, 242. 


8 CHEMICAL REAGENTS 


not be rendered turbid by the addition of barium chloride 
solution. 

Calcium. — 20 cc. of the 1:10 aqueous solution must not 
be rendered turbid by the addition of ammonium oxalate 
solution. 

Lead.* — A solution of 5 gm. of citric acid in 10 cc. of 
water, to which 12 cc. of ammonia water are added, should 
not acquire a dark color upon adding freshly made, saturated 
hydrogen sulphide water. 

Non-volatile Matter. — 1 gm. of citric acid must leave no 
weighable residue on ignition. 

Quantitative Determination. — On dissolving 1 gm. of citric 
acid in 30 ec. of water and titrating with normal potassium 
hydroxide solution, using phenolphthalein as indicator, not 
less than 14.2 ec. of the alkali solution should be required to 
develop the pink color. 

1 ee. of normal KOH = 0.07002 gm. of C,H,O, fs H,0, 
log. 84522. 


ACID GALLIC 
C:H2(OH);- (COOH) + H.0. Mol. Wt. 188.06. 


Colorless or slightly yellowish needles or prisms, which 
melt and slowly decompose at 220° C. Gallic acid dissolves 
in 130 parts of cold water, in 3 parts of boiling water, in 
5 parts of 95 per cent alcohol, and in about 40 parts of ether. 


TESTS OF PURITY 


Solubility in Water.— 1 gm. of gallic acid must dissolve 
completely in 20 cc. of water on heating. The solution must 
be colorless or only faintly yellowish. _ 

Water Content. — On drying 1 gm. of gallic acid at 100° C. 

* Regarding the examination of citric acid for lead compounds see 


M. Bucket, Ztschr. anal. Chem. 82, 465 (1893); J. Chem. Soc., 64, II, 
557 (1898). 


CHEMICAL REAGENTS 9 


to constant weight, it should not lose more than 0.1 gm. in 
' weight. 

Sulphuric Acid. — On adding 1 cc. of hydrochloric acid 
and some barium chloride solution to a 1:50 aqueous solu- 
tion of gallic acid, a precipitate of barium sulphate must not 


- form within an hour. 


Inorganic Matter.—1 gm. of gallic acid must leave no 
weighable residue on ignition. 


ACID *HYDRIODIC 
HI. Mol. Wt. 127.97. 


I 
ACID HYDRIODIC, SP. GR. 1.5 


A clear, colorless liquid which, on exposure, to light and 
air, rapidly becomes yellow to brown, due to the separation 
of iodine. Specific gravity 1.5. The liquid contains about 
43 per cent of HI. 


TESTS OF PURITY | 


Non-volatile Matter. — 5 gm. of hydriodic acid should leave 
no weighable residue on evaporation. 

Sulphuric Acid. — On diluting 5 gm. of hydriodic acid with 
50 cc. of water and adding barium chloride solution, no 
barium sulphate should precipitate on standing twelve 
hours. 

Heavy Metals and Earths. — On diluting 10 gm. of hydriodic 
acid with 100 cc. of water and passing hydrogen sulphide gas 
into a portion of the solution, no colored precipitate should 
form; and, after adding an excess of ammonia water to 
another portion of the solution, neither ammonium sulphide 
nor ammonium oxalate solution should cause a_ visible 
change. 


10 CHEMICAL REAGENTS 


Hydrochloric and Hydrobromic Acids. — Dilute 1 gm. of 
hydriodic acid with 20 cc. of water, add an excess of silver © 
nitrate solution followed by 30 cc. of ammonia water, shake 
well, and filter. On acidulating the filtrate with nitric acid, 
only a slight turbidity may develop, never a precipitate.* 

Quantitative Determination. — Dilute 5 gm. of hydriodic 
acid with 50 cc. of water and titrate with normal potassium 
hydroxide solution, using methyl orange as indicator. At 
least 17 ec. of the normal alkali solution must be required to 


effect the change in color. 
1 ce, of normal KOH = 0.12797 gm. of HI, log. 10710. 


II 
ACID HYDRIODIC, SP. GR. 1.70 


A yellow or brownish liquid of specific gravity 1.70. 
The acid contains about 57 per cent of HI and is used for 
methoxyl determination, according to Zeisel. 

TESTS OF PURITY 


Tests for non-volatile impurities and sulphuric acid are 
made, observing the conditions given above. In titrating 
this acid, phenolphthalein is used as the indicator. 


ACID HYDROBROMIC 
HBr. Mol. Wt. 80.96. 
A clear, colorless, or faintly yellowish liquid, of specific 
gravity 1.38. It contains about 40 per cent of HBr. 
; TESTS OF PURITY 
Non-volatile Matter.—10 gm. of hydrobromic acid on 


* A slight turbidity is permitted, because silver iodide is not absolutely 
insoluble in ammonia water. 


CHEMICAL REAGENTS 7 11 


evaporation on the water-bath should leave no weighable 
residue: 

Sulphuric Acid. — On diluting 5 gm. of hydrobromic acid 
with 50 ce. of water and adding barium chloride solution, a 
precipitate of barium sulphate should not form on standing 
twelve hours. 


Heavy Metals. — . 

(a) Dilute 10 gm. of pydohiroié acid with 10 cc. of 
water and overlay with hydrogen sulphide water; 
neither a coloration nor a yellow ring should form 
at the contact-surfaces of the two liquids on standing 
one hour. 

(b) Dilute 20 ec. of hydrobromic acid with 20 cc. of water, 
and add 30 cc. of ammonia water, followed by a 
few drops of ammonium sulphide and. ammonium 
oxalate solutions; on standing two hours neither a 
brown coloration nor a precipitate should appear. 

(c) Boil 5 gm. of hydrobromic acid with 25 cc. of water 
and 2 drops of nitric acid. No reddish color should 
occur on the addition of potassium sulphocyanate 
solution. ; 


Hydrochloric Acid. —2 or 3 drops of hydrobromic acid 
are diluted with 4 cc. of water, and then mixed with 15 ce. 
of decinormal silver nitrate solution. To this mixture add 
6 ce. of ammonium carbonate solution (1 part of ammonium 
carbonate, 1 part of ammonia water, and 3 parts of water), 
shake for five minutes, and filter. The filtrate acidulated 
with nitric acid may exhibit at most a faint turbidity. 

Hydriodic Acid. — To a mixture of 5 drops of hydrobromic 
acid, 5 ec. of water, and 10 ce. of ammonia water, add one 
drop of silver nitrate solution. The mixture after being 
shaken must remain clear, or at most may develop a turbidity 
insufficient to destroy entirely its transparency. 


12 CHEMICAL REAGENTS 


Besides the above test for hydriodic acid, the following 
may also be employed: 

On adding 1 drop of ferric chloride solution to 5 cc. of 
hydrobromic acid, and shaking with 5 cc. of chloroform, the 
latter should not acquire a violet color. 

Phosphorous and Phosphoric Acids. — Heat 1 gm. of hydro- 
bromic acid with 1 cc. of nitric acid to boiling, allow to cool, 
and then add 4 cc. of ammonia water followed by 1 drop of 
- magnesium sulphate solution. No precipitate should form 
even on standing two hours. 

Quantitative Determination. — Dilute 5 gm. of hydrobromic 
acid with 50 cc. of water, and titrate with normal potassium 
hydroxide solution, using methyl orange as indicator. At 
least 24.6 cc. of the normal alkali solution should be required 
to effect the change in color. 

1 ce. of normal KOH = 0.08096 gm. of HBr, log. 90827. 


ACID HYDROCHLORIC 
HCl. Mol. Wt. 36.45. 


I 
ACID HYDROCHLORIC. ‘SP. GR. 1.19 
(Fuminc HyprocH.Loric AcID) 


A clear, colorless liquid, fuming in the air, and of specific 
eravity 1.19. The liquid contains about 37 per cent of HCl. 


TESTS OF PURITY 


Sulphuric Acid. — Evaporate 100 gm. of hydrochloric acid 
in a platinum dish to about 5 cc., dilute the residue with 
water, and add barium chloride solution. No precipitate of 
barium sulphate should form on standing twelve hours. 

Non-volatile Matter. — 20 gm. of hydrochloric acid, when 
evaporated in a platinum dish on the water-bath, must leave 
no weighable residue. 


CHEMICAL REAGENTS 13 


Chlorine.* — Dilute 5 gm. of hydrochloric acid with 50 ce. 
of water and add zine iodide-starch solution. The liquid 
must not develop a blue color within ten minutes. 

Sulphurous Acid. — 50 ec. of water are colored blue by the 
addition of 1 drop of decinormal iodine solution and a few 
drops of starch solution. Then add a mixture containing 
5 gm. of the hydrochloric acid to be tested and 50 cc. of 
water. The liquid must not be decolorized after being 
shaken. 

Heavy Metals. — 

(a) Dilute 20 gm. of hydrochloric acid with 200 cc. of 
water, warm the liquid to about 70° C., and pass 
into it hydrogen, sulphide gas for twenty minutes. 
No precipitate should form within two hours. 

(b) Dilute 20 gm. of hydrochloric acid with 200 cc. of 
water, and add 50 ce. of ammonia water, followed 
by a few drops of ammonium sulphide solution. 
The mixture must not acquire a dark color, nor 
should a precipitate form. | 

(c) Boil 5 gm. of hydrochloric acid with 20 cc. of water 
and 2 drops of nitric acid. After cooling, a reddish 
color should not occur on the addition of potassium 
sulphocyanate solution. 

Calcium. — On diluting 20 ec. of hydrochloric acid with 
20 cc. of water and adding 50 cc. of ammonia water, followed 
by a few ec. of ammonium oxalate solution, no precipitate 
should form on standing two hours. : 

Arsenic. — Add 0.1 gm. of potassium chlorate to 200 gm. 
of hydrochloric acid, and evaporate on the water-bath. A 
Marsh apparatus is started, using 20 gm. of arsenic-free, 
granulated zine and dilute (1:5) sulphuric acid; then the 

* Regarding the testing for chlorine, see also Kupfferschliger, Bull. 


Soc. chim. Paris, (3), 2, 134 (1889) [Ztschr. anal. Chem., 31, 201 (1892)]; 
J. Chem. Soc., 58, 289 (1890). 


14 CHEMICAL REAGENTS 


residue from the above evaporation is washed into the gen- 
erating flask of the apparatus by the aid of dilute sulphuric 
acid. After the apparatus has been in action for one hour, 
there may be at most a very slight deposit in the reduction 
tube, but no distinctly visible arsenic mirror. 

Quantitative Determination.— The strength of the acid 
may be most simply ascertained from the specific gravity.* 

On diluting 3 gm. of hydrochloric acid with 50 cc. of water, 
and titrating with normal potassium hydroxide solution, 
using methyl orange as indicator, not less than 30.5 cc. of 
the normal alkali should be required to effect the color change. 

1 ce. of normal KOH = 0.036458 gm. of HCl, log. 56179. 


II 
ACID HYDROCHLORIC, SP. GR. 1.124 


(DitutED Hyprocuioric AcIp) 


A clear, colorless liquid, of specific gravity 1.124, and 
containing 25 per cent of HCl. 


TESTS OF PURITY 


The tests to be made are those given under Fuming Hy- 
drochloric Acid. But, instead of using 10 gm. of fuming 
acid, use 15 gm. of the acid of sp. gr. 1.124. 

Quantitative Determination. — Dilute 5 gm. of the acid 
with 50 cc. of water, and titrate with normal potassium 
hydroxide solution, using methyl orange as indicator. At 
least 34.3 cc. of the normal alkali should be required for 
neutralization. 


* See the table by Lunge and Marchlewski, in Lunge’s Chem.-techn. 
Untersuch.-Meth., 5 ed., 1, 419 (1904); U. S. Pharmacopeeia, VIII, p. 612 
(1905). Compare J. Soc. Chem. Ind., 24, 789 (1905). 


CHEMICAL REAGENTS 15 


Ill 


ACID HYDROCHLORIC, SP. GR. 1.050 


A clear, colorless liquid, of specific gravity about 1.050, 
and containing about 10 per cent of HCl. 


TESTS OF PURITY 


The tests to be made are those given under Fuming Hy- 
drochloric Acid. But, instead of using 10 gm. of the fuming 
acid, use 35 gm. of the 10 per cent acid. 


ACID HYDROFLUORIC 
HF. Mol. Wt. 20. 


A colorless, or almost colorless, liquid, containing 38 to 40 
per cent of HF. It fumes in the air. 


TESTS OF PURITY 


In these tests use platinum containers as much as possible. 

Non-volatile Matter. — 20 gm. of hydrofluoric acid evapo- 
rated in a platinum dish, and gently ignited, should leave a 
residue weighing not more than 0.001 gm. 

Sulphuric Acid. — Evaporate 2 gm. of hydrofluoric acid in 
a platinum dish on the water-bath, take up the residue with 
10 cc. of water, and to this solution add a few drops of nitric 
acid and some barium nitrate solution. An immediate tur- 
bidity must not occur; and even after some time the liquid 
should exhibit, at most, a slight opalescence. 

Calcium. — Dilute 5 gm. of hydrofluoric acid with 50 ce. of 
water and add ammonia water in excess, followed by ammo- 
nium oxalate solution. An immediate turbidity should not 
occur. 

Magnesium. — Dilute 5 gm. of hydrofluoric acid with 50 cc. 
of water, and add ammonia water until the liquid has an 


16 CHEMICAL REAGENTS 


alkaline reaction; on now adding ammonium phosphate solu- 
tion, no precipitate should form on standing three hours. 

Heavy Metals. — 

(a) Dilute 10 gm. of hydrofluoric acid with 40 cc. of water, 
warm the liquid, and saturate with hydrogen sul- 
phide gas. Neither a yellow nor a dark-colored 
precipitate should form. 

(b) Dilute 5 gm. of hydrofluoric acid with 50 cc. of water, 
make the solution alkaline with ammonia water, 
and add ammonium sulphide solution. A green 
coloration must not develop, nor should a precipitate 
form. 

Hydrochloric Acid. — Dilute 2 gm. of hydrofluoric acid 
with 50 cc. of water and add a few drops of nitric acid and 
silver nitrate solution. The liquid may exhibit, at most, a 
faint opalescence. 

Hydrosilicofluoric Acid. — On diluting 5 gm. of hydrofluoric 
acid with 20 ec. of water and adding 2 cc. of a cold, saturated 
potassium chloride solution, the further addition of 40 cc. of 
85 per cent alcohol should cause no turbidity or precipitate. 

Quantitative Determination. — Dilute 2 gm. of hydrofluoric 
acid with 50 cc. of water and titrate with normal potassium 
hydroxide solution, using phenolphthalein as indicator. 

1 cc. of normal KOH = 0.020 gm. of HF, log. 30103. 


Norte. — Regarding the titration of hydrofluoric acid, see Katz, Chem. 
Ztg., 28, 356, 387 (1904); J. Chem. Soc., 86, II, 442 (1904). 


ACID HYDROSILICOFLUORIC 


(FLUOSILICIC OR SILICOFLUORIC ACID) 
H2SiFs. Mol. Wt. 144.41. 
A clear, colorless liquid having a specific gravity of about 


1.06. This specific gravity corresponds to a content of 7.5 
per cent of H,SiF,. 


CHEMICAL REAGENTS 17 


TESTS OF PURITY 


Non-volatile Matter. — 5 gm. of hydrosilicofluoric acid evap- 
orated in a platinum dish should leave no weighable residue. 

Heavy Metals. — Dilute 5 gm. of hydrosilicofluorie acid 
with 10 cc. of water, add a few drops of hydrochloric acid 
nd 10 cc. of hydrogen sulphide water. No visible change 
should take place. 

Sulphuric Acid. — On diluting 5 gm. of hydrosilicofluorie 
acid with 10 ec. of water and adding a solution of barium-free 
strontium nitrate, no precipitate should form, even on stand- 
ing twelve hours. | 


Note. — Regarding the determination of hydrosilicofluoric acid, see 
Katz, Chem. Ztg., 28, 356, 387 (1904); J. Chem. Soc., 86, II, 442 (1904). 


ACID IODIC 
. HIOs. Mol. Wt. 175.97. 


Colorless, rhombic crystals, or white, crystalline powder, 
easily soluble (1:1) in water, but difficultly soluble in alcohol. 
The aqueous solution first reddens blue litmus paper and 
then bleaches it. 


TESTS OF PURITY 


Non-volatile Matter. — On heating 2 gm. of iodic acid no 
- weighable residue should remain. | 

Solubility. — 1 gm. of iodic acid should dissolve completely 
in 1 cc. of water, and yield a colorless solution. 

Quantitative Determination. — Dissolve 1 gm. of iodic acid 
in water and dilute to 100 ce. Dilute 10 ce. of this solution 
with 50 ec. of water, and add 2 gm. of potassium iodide and 
5 ec. of dilute sulphuric acid. Titrate the liberated iodine 
with decinormal sodium thiosulphate solution, using starch 
solution as indicator. 

1 ec. of decinormal Na,S,O, = 0.002933 gm. of HIO,, log. 
46731. 


18 : CHEMICAL REAGENTS 


(ACID) IODIC ANHYDRIDE 


(LoDINE PENTOXIDE) 

1,0;. Mol. Wt. 333.94. 
A white, crystalline powder, soluble in water with the 
formation of the hydrated acid, HIO,, but insoluble in abso- 
lute alcohol, ether, and carbon disulphide. : 


TESTS OF PURITY 
The tests to be made are those given under Iodic Acid. 
1 cc. of decinormal Na,S,O, = 0.00278283 gm. of I,0,, 
log. 4448. 
ACID MOLYBDIC 
H.MoO,. Mol. Wt..162.01. 


A white or slightly yellowish powder, containing about 
85 per cent of MoQ,. 


TESTS OF PURITY 

Solubility in Ammonia Water; Heavy Metals. —2 gm. of 
molybdic acid should completely dissolve in a mixture of 
10 cc. of water and 5 cc. of ammonia water (sp. gr. 0.91), 
yielding a clear solution. On the addition of hydrogen 
sulphide water to this liquid it acquires a slight yellow color; 
a green color or a precipitate should not, however, develop. 

Phosphoric Acid. Quantitative Determination. — As de- 
tailed under (Acid) Molybdic Anhydride, below. 


(ACID) MOLYBDIC ANHYDRIDE 


(Motyspic Acip, 100%) 
MoO;. Mol. Wt. 144. 

A slightly yellowish powder, often exhibiting a faintly 
bluish tint, due to the presence of other oxides of molybde- — 
num. The preparation contains about 100 per cent of MoO,, 
and is free from ammonia and nitric acid. 


CHEMICAL REAGENTS 19 


TESTS OF* PURITY 


Alkalies. — On heating 1 gm. of molybdie anhydride in a 
test tube, the particles adhering to the heated portion begin 
to fuse at a red heat, while at the upper, cooler portion of 
the tube a crystalline formation of sublimed anhydride may 
be observed. If the molybdic anhydride is contaminated 
with salts of the alkalies, the whole melts to a dark-colored 
mass. In such case the melting-point is low. 

Ammonium Salts. — On boiling 1 gm. of molybdiec anhy- 
dride with sodium hydroxide solution, there must be no 
liberation of ammonia (to be ascertained by means of moist- 
ened litmus paper). | 

Solubility in Ammonia Water; Heavy Metals. — 2 om. of 
molybdie anhydride, when gently heated with a mixture of 
10 cc. of water. and 5 cc. of ammonia water (sp. gr. 0.91), 
should entirely dissolve, yielding a clear solution. The solu- 
tion acquires a slight yellow color on adding hydrogen sulphide 
water. This color must not change within ten minutes nor 
should a precipitate form. 

Phosphoric Acid. — Dissolve 10 gm. of molybdie anhydride 
in 25 ec. of water and 15 cc. of ammonia water (sp. gr. 0.91). 
The solution, mixed with 150 cc. of nitric acid, and allowed 
to stand for two hours at a temperature of about 40° C., 
must not contain a yellow precipitate. 

Nitric Acid. —Shake 1 gm. of molybdic anhydride with 
10 cc. of water, and add a small crystal of sodium chloride, 
followed by one drop of a 1: 1000 solution of indigo; the blue 
color of the solution must not disappear on adding 10 ce. of 
concentrated sulphuric acid. 

Quantitative Determination. — Dissolve 0.5 gm. of molybdic 
anhydride in a mixture of 50 ec. of water and 1 cc. of am- 
monia water (sp. gr. 0.91), with the aid of a gentle heat. 
Acidulate the solution with 5 cc. of acetic acid (sp. gr. 1.041), 


20 CHEMICAL REAGENTS 


dilute with 200 cc. of water, heat to boiling, then add a 
solution of 1.5 gm. erystallized lead acetate in 20 cc. of 
water. Boil for several minutes with constant stirring, 
whereby the precipitate, at first milky, is rendered granular 
and easy to filter. Collect the precipitate on a filter, pre- 
viously dried at 100° C. and weighed, and wash it with boiling 
water until the washings cease to afford a reaction with 
hydrogen sulphide water. Dry the precipitate to constant 
weight at 100° C. and then ignite a portion of it. The ignited 
residue has the composition PbMoQ,. 
PbMoO, X 0.39247 = MoO,, log. 59380. 


ACID NAPHTHYLAMINESULPHONIC 


(ALPHANAPHTHYLAMINESULPHONIC AcID; NAPHTHIONIC 
AcIp) 
CicHo(NH2)(SO3H)1: 4 + $H:O0. Mol. Wt. 232.18. 

A white powder, or small, lustrous, colorless needles (when 
crystallized from hot water), which carbonize but do not 
melt on being heated. Naphthylaminesulphonic acid is 
soluble in about 4000 parts of cold water, more readily in 
hot water, scarcely soluble in alcohol, and insoluble in ether. 
The solution in ammonia water exhibits a violet fluorescence. 


Notre. — Regarding the use of naphthylaminesulphonic acid for the 
detection and colorimetric determination of small quantities of nitrous 
acid, see E. Riegler, Ztschr. anal. Chem., 35, 677 (1896) [or Merck’s Rea- 
gentien-Verzeichnis (1903), p. 120]; J. Chem. Soc., 72, II, 230 (1897). 
E. Riegler, Ztschr. anal Chem., 36, 306 (1897); J. Chem. Soc., 72, II, 
385 (1897). . 

ACID NITRIC 


HNOs. Mol. Wt. 63.04. 
I 
ACID NITRIC, SP. GR. 1.40 


A clear, colorless liquid, specific gravity 1.40 to 1.42, and 
containing about 68 per cent by weight of HNO. 






OF, THE 
UNIV ERGITY 
mC A LI row 
CHEMICAL REAGENTS 21 





TESTS OF PURITY 


Non-volatile Matter. — 4 cc. of nitric acid on evaporation 
should leave no weighable residue. 

Sulphuric Acid. — Dilute 4 cc. of nitric acid with 90 cc. ‘of 
water, and add barium chloride solution. No precipitate of 
barium sulphate should form on standing twelve hours. 

Hydrogen-Halogen Acids.—4 cc. of nitric acid diluted with 
90. cc. of water must not appear changed on the addition of 
silver nitrate solution. 

Heavy Metals, and Earths. — Dilute 8 cc. of nitric acid 
with 80 cc. of water, and render slightly alkaline with am- 
monia water. On adding a few drops of ammonium sul- 
phide and ammonium oxalate solutions, neither a dark 
color nor a turbidity should result. 

Iodic Acid and Iodine. — On diluting 2 ce. of nitric acid 
with 10 cc. of water, adding a small piece of metallic zinc, 
and shaking with a small quantity of chloroform, the chloro- 
form should not be colored violet. 

Quantitative Determination. — Dilute 2 gm. of nitric acid 
with 50 cc. of water and titrate with normal potassium 
hydroxide solution, using methyl orange as indicator. 

1 cc. of normal KOH = 0.06304 gm. of HNO,, log. 79962. 


II 
ACID NITRIC, SP. GR. 1.30 


A clear, colorless liquid, of specific gravity 1.30, and con- 
taining about 47 per cent of HNO,. 


TESTS OF PURITY 
The tests to be made are those given under Acid Nitric sp. 
gr. 1.40, observing the conditions there described. But in- 
stead of 4 cc. of the acid sp. gr. 1.40, 7.5 cc. of. the acid 
sp. gr. 1.30 are to be used. 


22 CHEMICAL REAGENTS 


} III 
ACID NITRIC, SP. GR. 1.20 - 
A clear, colorless liquid, of specific gravity 1.20, and con- 
taining about 33 per cent of HNO,. 
TESTS OF PURITY 


The tests to be made are those given under Acid Nitric 
sp. gr. 1.40, observing the conditions there described. But, 
instead of 4 cc. of acid sp. gr. 1.40, 10 cc. of acid sp. gr. 
1.20 are to be used. 


IV 
ACID NITRIC, SP. GR. 1.153 
A clear, colorless liquid, of specific gravity 1.153, and 
containing about 25 per cent of HNO,. 
TESTS OF PURITY 


The tests to be made are those given under Acid Nitric 
sp. gr. 1.40, observing the conditions there described. But 
instead of 4 cc. of acid sp. gr. 1.40, 13 ce. of acid <P. er. 1.153 
are to be used. 


ACID NITRIC, CRUDE, SP. GR. 1.38 


A clear, colorless, or yellowish liquid of specific gravity 
1.380-1.40, and containing at least 61 per cent of HNQ,. 
TESTS OF PURITY 
Non-volatile Matter. — 5 cc. of crude nitric acid on evapo- 
ration should leave no weighable residue. 


ACID NITRIC, FUMING, SP. GR. 1.486 


A yellow, or reddish-yellow, clear liquid of specific gravity 
1.486-1.500, and containing at least 86 per cent of nitric 
acid, HNQs,. ) 


CHEMICAL REAGENTS 23 


TESTS OF PURITY 


The tests to be made are those given under Acid Nitric 
sp. gr. 1.40. But for 4 cc. of acid sp. gr. 1.40, use 5 cc. of 
fuming nitric acid. 


ACID OXALIC 
H.C.0, + 2H:O. Mol. Wt. 126.04. 

Colorless, odorless, prismatic crystals, free from efflores- 
cence. Crystallized oxalic acid is soluble in 10 parts of cold, 
and in about 3 parts of boiling, water, in 2.5 parts of alcohol, 
and in about 100 parts of ether. On heating the hydrated 
oxalic acid in a capillary tube, it liquefies at 98° C. in its 
water of crystallization. On being heated to 70° C., the 
hydrated acid is rendered anhydrous, which latter sublimes 
at about 100° C. and melts at 187° C. This preparation must 
contain 99.8-100 per cent of the hydrated acid, H,C,O, + 
2 H,0. 3 


TESTS OF PURITY 


Ash. — 3 gm. of oxalic acid, after being dried and then © 
ignited in a platinum crucible, should leave no weighable 
residue. 

Sulphuric Acid. — Dissolve 5 gm. of oxalic acid in 100 ce. 
of water, and add 1 ce. of hydrochlori¢ acid and 1 ee. of 
barium chloride solution. No precipitate of barium sulphate 
should form on standing twelve hours. 

Chlorides. — Dissolve 5 gm. of oxalic acid in 50 cc. of 
-water, add 15 cc. of nitric acid and a few drops of silver 
nitrate solution. The solution may exhibit at most a slight 
opalescent turbidity. 

Heavy Metals. — The 1:10 aqueous solution must be per- 
fectly clear, and on adding hydrogen sulphide water to 30 ce. 
of it, no reaction should be observed. On now adding 


24 CHEMICAL REAGENTS 


ammonia water to this liquid until alkaline, neither a green 
nor a brown coloration should develop, nor should a precipitate 
form. 

Ammonium Compounds. — 

(a) The solution of 5 gm. of crystallized oxalic acid in 
30 ec. of sodium hydroxide solution on being boiled 
should not evolve ammonia (to be ascertained by 
means of moistened litmus paper). 

(b) On dissolving 2.5 gm. of oxalic acid and 5 gm. of 
potassium hydroxide in 30 cc. of water, and adding 
to the solution about 15 drops of Nessler’s reagent, 
at most a slight yellow color should develop; never a 
brownish-red color. 

Nitric Acid. — On overlaying 10 cc. of a solution of dipheny- 
lamine in concentrated sulphuric acid with 10 ee. of a 1:10 
aqueous solution of oxalic acid, a blue zone should not form 
at the contact-surfaces of the two liquids. 

Quantitative Determinations. — 

(a) Acidimetrically: Dissolve about 6.3 gm. of crystallized 

oxalic acid in water, dilute to 500 cc., and titrate 
25 cc. of the solution with one fifth normal potassium 
hydroxide solution, using phenolphthalein as indi- 
cator. Perform the titration at 60° C. 

1 ce. of fifth normal KOH = 0.012605 gm. of H,C,O, + 
2H,0, log. 10055. 

(b) By Oxidimetry: To 25 ec. of the aqueous solution (6.5 
em. of crystallized oxalic acid in water as above) 
add 6 to 8 cc. of concentrated sulphuric acid, heat 
to about 60° C., and titrate with decinormal potas- 
sium permanganate solution. 

1 ec. of decinormal KMnO, = 0.0063024 gm. of H,C,O, + 

2H,0, log. 79950. 


CHEMICAL REAGENTS 25 


ACID OXALIC, SUBLIMED 
H:C:0.. Mol. Wt. 90.01. 
A white, crystalline, exceedingly hygroscopic powder, 
melting at 187° C. The preparation must contain at least 
99.5 per cent of anhydrous oxalic acid, H,C,Q,. 


TESTS OF PURITY 


Ash. — 10 gm. of the oxalic acid on ignition should leave 
no weighable residue. 

Other Tests. — The other tests to be made are those given 
under crystallized oxalic acid. 

1 ce. of fifth normal KOH = 0.009001 gm. of H,C,O,, 
log. 95432. 

1 ec. of decinormal KMnO, = 0.0045008 gm. of H,C,O,, 
log. 65329. 


Notre. —If it is desired to use sublimed oxalic acid for standardizing 
solutions for alkalimetric or oxidimetric determinations, it must be heated 
to dryness at a temperature of 60 to 70° C., in small quantities at a time. 


ACID PERCHLORIC 
HClO,. Mol. Wt. 100.45. 


A colorless liquid of specific gravity 1.12, and containing 
about 20 per cent of HCIO,. 


TESTS OF PURITY 


Non-volatile Matter.— 10 gm. of perchloric acid when 
evaporated and ignited should leave no weighable residue. 

Sulphuric Acid. — On diluting 5 ce. of perchloric acid with 
100 cc. of water, and adding 1 cc. of hydrochloric acid, fol- 
lowed by barium chloride solution, a precipitate of barium 
sulphate should not form on standing twelve hours. 

Hydrochloric Acid. — The mixture obtained by diluting 
5 ec. of perchloric acid with 25 cc. of water and adding 3 cc. 


26 CHEMICAL REAGENTS 


of nitric acid should not be rendered more than slightly 
turbid by silver nitrate solution. 

Barium. — 10 ce. of perchloric acid diluted with 50 cc. of 
water must not become turbid within five minutes on adding 
dilute sulphuric acid. 

Heavy Metals. —10 cc. of perchloric acid dilated with 
40 cc. of water must show no change on adding hydrogen 
sulphide water; and on adding to this solution 10 cc. of 
ammonia water, and a few drops of ammonium sulphide 
solution, a precipitate should not form, nor should the liquid 
acquire a green or brown color. 


ACID PHOSPHOMOLYBDIC 
12Mo00; . H;PO, + 2H,0. 


Yellow, lustrous crystals, easily and completely soluble in 
water, and yielding with the latter an acid solution. 


TESTS OF PURITY 


Solubility, Heavy Metals, and Earths. — 1 gm. of phospho- 
molybdic acid should completely dissolve in 10 cc. of water. 
On adding to this solution two or three drops of ammonia 
water, a yellow precipitate forms, which completely redis- 
solves on the addition of 5 cc. of the ammonia water. On 
now adding to this solution ammonium sulphide and ammo- 
nium oxalate solutions, no visible change should take place. 


ACID PHOS? HORT C 


(Ortho.) 
HsPO,. Mo. Wt. 98.02. 


I 
ACID PHOSPHORIC, SP. GR. 1.7 


A clear, colorless, odorless, syrupy liquid, of specific gravity 
1.7, and containing about 85 per cent of H,PQO,. 


CHEMICAL REAGENTS 27 


TESTS OF PURITY 


Volatile Acids. — Mix 30 cc. of the phosphoric acid with 
50 ce. of water in a distilling flask. Distil * off 50 ec., and 
titrate the distillate with decinormal potassium hydroxide 
solution, using methyl orange as indicator. Not more than 
0.1 ec. of the decinormal alkali solution should be required. 
Nitric Acid. — 2 cc. of phosphoric acid mixed with 2 cc. of 
concentrated sulphuric acid, and overlaid with 1 ce. of a 
solution of ferrous sulphate, must not develop a colored zone. 
Hydrogen-Halogen Acids and Phosphorous Acid. — 2 cc. of 
phosphoric acid diluted with 18 cc. of water should give no 
reaction with silver nitrate solution either in the cold or on 
warming. 
Sulphuric Acid. — On adding barium chloride solution to 
20 ce. of the diluted acid (1:10), no precipitate of barium 
sulphate should form on standing two or three hours. 
Metaphosphoric Acid. — On dropping the acid diluted with 
10 volumes of water into a dilute solution of albumen, no 
turbidity should ensue. 
Heavy Metals, Earths, Etc. — 
(a) Dilute the acid with 10 volumes of water, and to 20 ce. 
of the mixture add hydrogen sulphide water. There 
should be no visible change. 7 

(b) On adding 10 cc. of ammonia water to 20 cc. of the 
above diluted acid, no precipitate should form on 
the further addition of either ammonium oxalate 
solution, or ammonium sulphide solution. 

(c) A mixture of 5 ce. of phosphoric acid with 20 cc. of 

absolute alcohol should remain perfectly clear. 

Substances Oxidizable by Permanganate.— On adding 5 


* In order to prevent spirting over of phosphoric acid, the flask should 
be provided with a Kjeldahl connecting bulb tube. The distillate must 
be tested with ammonium molybdate solution for phosphoric acid. 


28 CHEMICAL REAGENTS 


drops of decinormal potassium permanganate solution to a 
mixture of 5 ec. of phosphoric acid and 5 ce. of diluted sul- 
phuric acid, and then heating for five minutes at 100° C., 
the red color of the liquid should not disappear. 

Arsenic. — A Marsh apparatus is started using 20 gem. of 
-arsenic-free, granulated zinc, and diluted (1:5) sulphuric 
acid. A mixture of 3 ec. of phosphoric acid with 20 ce. of 
water is then introduced in small quantities at a time, the 
evolution of hydrogen being maintained for about two hours. 
A deposit of arsenic should not be visible in the reduction 
tube within these two hours. 

Quantitative Determination. — Dilute 1 gm. of phosphoric 
acid with 30 cc. of water, and titrate with normal potassium 
hydroxide, using phenolphthalein as indicator.* At least 
17 ec. of normal alkali must be added to produce the red 
color. 

1 ce. of normal KOH = 0.04901 gm. of H,PO,, log. 69028. 


II 


ACID PHOSPHORIC, SP. GR. 1.12 


A clear, colorless, odorless liquid of specific gravity 1.12, 
and containing about 20 per cent of H,POQO,. 


TESTS OF PURITY 


The tests to be made are those given under Acid Phos- 
phoric sp. gr. 1.7. But for 1 ec. of the phosphoric acid 
sp. gr. 1.7, use 4 ec. of the phosphoric acid sp. gr. 1.12. 


* Methyl orange may be used instead of phenolphthalein. In this case, 
however, 1 cc. of the normal KOH = 0.09802 gm. of H3PQu:, log. 99131. 
When titrating with phenolphthalein, twice as many cubic centimeters 
of the alkali solution are required as when using methyl orange. 


CHEMICAL REAGENTS 29 


al 
ACID PHOSPHORIC, SP. GR. 1.057 


A clear, colorless, odorless liquid of specific gravity about 
1.057, and containing about 10 per cent of H,PQ,. 


TESTS OF PURITY 


The tests to be made are those given under Acid Phos- 
phoric sp. gr. 1.7. But for 1 cc. of the acid sp. gr. 1.7, 
use 10 cc. of the acid sp. gr. 1.057. 


(ACID) PHOSPHORIC ANHYDRIDE 


(PHOSPHORUS PENTOXIDB) 
P.O;. Mol. Wt. 142.00. 

A white, amorphous, odorless, bulky powder, which dis- 
solves in water with a hissing noise, forming metaphosphoric 
acid. Phosphoric anhydride completely sublimes on being 
heated. 


TEST OF PURITY 


Arsenous Acid. — Introduce 1 gm. of phosphoric anhydride, 
in small portions at a time, into 20 ce. of water, and while 
warming the solution, pass into it a current of hydrogen 
sulphide gas. The liquid should not acquire a yellow color, 
nor should a yellow precipitate form. 


ACID PHOSPHORIC, META 


(GLACIAL PHospHoRIC ACID) 
HPOs;. Mol. Wt. 80.0. 
Colorless, transparent, vitreous pieces or sticks, deliquescent 
in moist air, and melting to a clear viscid liquid on being 
warmed. Metaphosphoric acid is very easily soluble in water. 


30 CHEMICAL REAGENTS 


TESTS OF PURITY 


Nitric Acid. -- On adding 2 cc. of concentrated sulphuric 
acid to a solution of 1 gm. of metaphosphorie acid in 2 ce. 
of water, and overlaying the mixture with 1 cc. of a solution 
of ferrous sulphate, no colored zone should form. 

Sulphuric Acid. — The solution of 1 gm. of metaphosphoric 
acid in 20 cc. of water must not immediately be rendered 
turbid on the addition of 5 cc. of hydrochloric acid, followed 
by barium chloride solution. 

Hydrogen-Halogen Acids. — Add 5 cc. of nitric acid to a 
solution of 1 gm. of metaphosphorie acid in 20 cc. of water. 
On the further addition of silver nitrate solution the liquid 
should appear unchanged. 

Heavy Metals, Earths, Etc. — 

(a) The solution of 1 gm. of metaphosphoric acid in 20 ce. 
of water must not be affected by hydrogen sulphide 
water. 

(b) On adding 5 ec. of ammonia water to a solution of 
1 gm. of metaphosphoric acid in 20 cc. of water, no 
precipitate should form on adding ammonium oxalate 
and ammonium sulphide solutions. 

Arsenic. — On adding 5 ce. of stannous chloride solution 
to a solution of 1 gm. of metaphosphoriec acid in 1 cc. of 
water, the mixture should not darken on standing one hour. 

Substances Oxidizable by Permanganate. — Dissolve 1 gm. 
of metaphosphoric acid in 10 ce. of water, add 5 cc. of 16 
per cent sulphuric acid and 0.1 ce. of decinormal potassium 
permanganate solution; then heat 5 minutes at 100° C. The 
red color of the mixture should not disappear. 


ACID PHOSPHOTUNGSTIC 
(P.0;-20WO,-11H.0) + 16H:O. Mol. Wt. 5268.43. 
Small, white, or slightly yellowish-green crystals, easily 
soluble in water, and free from ammonia and nitric acid. 


CHEMICAL REAGENTS 31 


TESTS OF PURITY 


Nitrates. — Dissolve 1 gm. of phosphotungstic acid in 10 ce. 
of water, add a granule of sodium chloride and 1 drop of 
indigo solution (1: 1000), followed by 10 cc. of concentrated : 
sulphuric acid. The blue color of the mixture must not 
disappear within ten minutes. 

Ammonium Salts. — On heating a solution of 1 gm. of 
phosphotungstic acid in 10 cc. of water, with 5 cc. of sodium 
hydroxide solution (sp. gr. 1.3), no ammonia should be 
evolved (to be ascertained by means of dampened litmus 
paper). 

Notre. — Regarding a method for the quantitative analysis of phos- 


photungstic acid, see F. Kehrmann, Ber., 20, 1813 (1887); J. Chem. Soc., 
52, 777 (1887). 


ACID PICRIC 


(Picronitric Acip; TRINITROPHENOL) 
CeH2(OH)(NOz)s. Mol. Wt. 229.14. 

Pale yellow, glistening crystals, melting at 122.5° C., 
soluble in about 90 parts of cold water and in about 30 parts 
of boiling water. The acid is readily soluble in alcohol, 
ether, and benzene, | 


TESTS OF PURITY 


Resins; Substances Insoluble in Water.—1 gm. of picric 
acid should dissolve completely and without turbidity in 
100 ce. of water. On adding to the solution 1 or 2 drops of 
16 per cent sulphuric acid, no precipitate should form on 
standing twelve hours. On subsequently filtering the liquid, 
no resin should remain on the filter. | 

Picrates of Potassium, Sodium, and Ammonium.* —1 gm. of 

* Picric acid cannot be tested for ammonia by warming with sodium 


hydroxide solution, as under such conditions picric acid itself decomposes 
with the evolution of ammonia. | 


32 CHEMICAL REAGENTS 


picric acid must completely dissolve in 20 cc. of benzene, 
affording a clear solution. 

Oxalic ‘Acid. — On adding calcium chloride solution to a 
solution of 1 gm. of picric acid in 100 cc. of water, a precipitate 
of calcium oxalate should not form within two hours. 

Free and Combined Sulphuric Acid. — Evaporate a mixture 
of 2 gm. of picric acid and 10 ce. of nitric acid (sp. gr. 1.4) 
to dryness on the water-bath. Dissolve the residue in 100 ce. 
of boiling water with the addition of 5 cc. of nitric acid, 
allow to cool, then filter, and add barium nitrate solution to 
the filtrate. There should be no immediate turbidity. 

Inorganic Matter (Ash). — 1 gm. of picric acid cautiously 
incinerated in an open platinum dish should not leave a 
residue weighing more than 0.001 gm. 


ACID ROSOLIC 
(CORALLIN) 


Brittle, amorphous, reddish-brown pieces, presenting a 
metallic reflection, and readily soluble in alcohol, but insoluble 
in water. 

Rosolic acid is used as an indicator in the form of a solution 
of 0.5 gm. of the acid in a mixture of 50 cc. of 85 per cent 
alcohol and 50 cc. of water. 


TESTS OF SENSITIVENESS 


Add two or three drops of the above rosolic acid solution 
to 100 cc. of distilled water. On adding to the solution 
0.05 ec. of decinormal potassium hydroxide, the pale-yellow 
color of the water should change to a rose-red, and on the 
further addition of 0.05 ec. of decinormal hydrochloric acid, 
the original color should be restored. 


CHEMICAL REAGENTS 33 


ACID SUCCINIC 
CsH Ou. Mol. Wt. 118.04. 


Colorless, monoclinic prisms, soluble in 20 parts of cold 
and about 2 parts of boiling water; in 10 parts of alcohol 
and in 80 parts of ether. Succinic acid melts at 182° C., 
and at 235° C. it boils with the evolution of white acrid 
fumes, while it undergoes decomposition to a large extent 
into water and succinic anhydride. 


TESTS OF PURITY 


Non-volatile Matter. — 1 gm. of succinic acid heated in a 
platinum dish should volatilize and leave no weighable 
residue; nor should any charring occur. 

Oxalic Acid. — The solution of 1 gm. of succinic acid in 
20 ec. of water should not be affected by calcium chloride 
solution. 

Tartaric Acid and Sulphates. — On adding potassium acetate 
and barium nitrate solutions to a solution of 1 gm. of succinic 
acid in 20 ce. of water, no precipitate should form on standing 
twelve hours. 

Chlorides. — On adding 2 or 3 ce. of nitric acid to 20 ce. 
of the 1:20 aqueous solution of succinic acid, not more than 
a faint opalescent turbidity should develop on the addition 
of silver nitrate solution. 

Ammonium Salts. — 1 gm. of succinic acid, on being heated 
with 10 ec. of sodium hydroxide solution (sp. gr. 1.3), should 
liberate no ammonia (to be ascertained with moist litmus 
paper). 

Heavy Metals. — 1 gm. of succinic acid dissolved in 20 ce. 
of water should not be visibly changed by hydrogen sulphide 
water. 

Quantitative Determination. — Dissolve 1 gm. of succinic 


34 CHEMICAL REAGENTS 


acid in 50 cc. of water, and titrate with normal potassium 
hydroxide, using phenolphthalein as indicator. : 
1 ce. of normal KOH = 0.05902 gm. of C,H,O,, log. 77100. 


ACID SULPHANILIC 
CoHi(NH2)(SOsH)1:4 + 2H,0. Mol. Wt. 209.18. 
Sulphanilic acid occurs in colorless, acicular, efflorescent 
crystals. It has no melting-point, but carbonizes on being 
heated to 280 to 300° C. The acid is difficultly soluble in 
cold water (about 150 parts), but more readily soluble in 
hot water; it is insoluble in alcohol, ether, and benzene. 


TESTS OF PURITY 


Inorganic Matter. — 1 gm. of sulphanilic acid should leave 
no weighable residue on ignition. 

Sulphuric Acid (Aniline Sulphate). — A solution of 1 gm. 
of sulphanilic acid in 25 ce. of boiling water should not change 
in appearance on adding a few drops of barium chloride 
solution. 

Hydrochloric Acid (Aniline Hydrochloride). On shaking 
1 gm. of sulphanilic acid with 20 cc. of water and filtering, 
the filtrate should exhibit at most a faint opalescent tur- 
bidity on the addition of a few drops of nitric acid and silver 
nitrate solution. 


ACID SULPHURIC 
H,SO,. Mol. Wt. 98.07. 


I 
ACID SULPHURIC, SP. GR. 1.84 
(CONCENTRATED SULPHURIC ACID) 
A clear, colorless, oily liquid of specific gravity 1.84, and 
containing 95 to 96 per cent of H,SQ,. 


CHEMICAL REAGENTS 35 


TESTS OF PURITY 


Non-volatile Matter. — 10 cc. of sulphuric acid, on being 
evaporated and ignited, should leave no weighable residue. 

Nitric Acid. — Dilute 1 cc. of sulphuric acid with 9 cc. of 
water, and overlay this liquid on 5 cc. of diphenylamine 
solution (see Diphenylamine, page 100). A blue zone should 
not form at the contact-surfaces of the two liquids. 

Selenium. — On overlaying 2 cc. of sulphuric acid with 
2 ee. of hydrochloric acid, in which a granule of sodium 
sulphite has been dissolved, a reddish zone must not form at 
the contact-surfaces of the two liquids; nor should a red 
precipitate form on warming. 

Substances Oxidizable by Permanganate. (Nitrous and 
Sulphurous Acids). — Dilute 15 cc. of sulphurie acid with 
60 cc. of water, and color the solution by adding 1 drop of 
decinormal potassium permanganate solution. The pink 
color should not disappear within three minutes. 

Hydrogen-Halogen Acids. — 2 cc. of sulphuric acid diluted 
with 30 cc. of water should appear unchanged on adding a 
few drops of silver nitrate solution. 

Lead. — On cautiously diluting 10 cc. of sulphuric acid 
with 50 cc. of 85 per cent alcohol, no turbidity should be 
observed; nor should a precipitate of lead sulphate form on 
standing two hours. 

Heavy Metals and Calcium. — 

(a) Dilute 10 cc. of sulphuric acid with 50 ec. of water, 

and add ammonia water in excess. On now adding 
a few drops of ammonium sulphide and ammonium 
oxalate solutions, neither a green color nor a turbidity 
should occur. 

(b) On diluting 20 cc. of sulphuric acid with 100 cc. of 

water, and passing a current of hydrogen sulphide 
gas into the solution, no brown color should develop; 


36 CHEMICAL REAGENTS 


nor, after the passage of the gas, should any brown 
flocks precipitate on long standing (Tin). 

Ammonium Salts. — Dilute 2 cc. of sulphuric acid with 
30 cc. of water, and add aqueous solution of potassium 
hydroxide (1:6) to alkalinity, followed by 10 to 15 drops of 
Nessler’s reagent. At most a light-yellow precipitate may 
form, but in no case a brownish-red one. 

Arsenic.* — A Marsh apparatus is set in operation, using 
20 gm. of arsenic-free, granulated zinc, and arsenic-free, 
dilute sulphuric acid (1:5). As soon as the air has been 
expelled from the apparatus, heat the reduction tube to 
redness, and then introduce a cooled mixture of 10 cc. of 
the acid (sp. gr. 1.84) to be tested and 50 cc. of water. No 
deposit of arsenic should be visible in the reduction tube 
within half an hour. 

Quantitative Determination.— The content of H,SO, is 
most readily ascertained by taking the specific gravity, and 
then referring to tables for the percentage. Consult the tables 
of Lunge, Isler, and Naef, Chem.-tech. Untersuch. — Meth., 
5 ed., 1, 354 (1904); compare Watts’ Dict. of Chem., 4, 621 
(1894); also J. Soc. Chem. Ind., 24, 790 (1905). 

The acid content may also be ascertained by titration with 
normal potassium hydroxide solution, using methyl orange as 
indicator. ; 

1 ec. of normal KOH = 0.049038 gm. of H,SO,, log. 69053. 


II 


ACID SULPHURIC, DILUTED 16% 


A colorless liquid of specific gravity 1.110 to 1.114, and 
containing 15.7 to 16.3 per cent of H,SQ,. 


* Regarding the detection of arsenic in sulphuric acid, see Lunge, 
Chem.-tech. Untersuch.-Meth., 5 ed., 1, 367 (1904); Detection and Deter- 
mination of Arsenic. Reprint from J. Soc. Chem. Ind., 1901. 


CHEMICAL REAGENTS i 37 


TESTS OF PURITY 


The tests to be made are those given under Acid Sulphuric 
sp. gr. 1.84. But for 1 cc. of the acid sp. gr. 1.84 use 9 ce. 
of the acid sp. gr. 1.110. 


Il 


ACID SULPHURIC, 10% 


A colorless liquid of specific gravity about 1.070, and 
containing about 10 per cent of H,SQ,. 


TESTS OF PURITY 


The tests to be made are those given under Acid Sulphuric, 
sp. gr. 1.84. But for 1 cc. of the acid Sp. gr. 1.84, use 15 ce. 
of the acid sp. gr. 1.070. 


(ACID) SULPHURIC ANHYDRIDE 


(SULPHUR TRIOXIDE) 
SO3. Mol. Wt. 80.06. 


Long, transparent, colorless prisms, which melt at 15° C. 
to a clear oily liquid, boiling at 46° C. On long keeping at 
a temperature below 25° C., the sulphuric anhydride po- 
lymerizes to a modification which forms long, silky, felted 
needles, which melt above 50° C., and which at a higher 
temperature become converted ints the trioxide in oe 
form, solidifying at 15° C., and boiling at 46° C. 


Norsr. — Regarding the quantitative determination of sulphuric anhy- 
dride, see the statements given under Acid Sulphuric, Fuming. Also R. 
Rosenlecher, ‘‘ Zur Gehaltsbestimmung der rauchenden Schwejelséure und 
des Schwefelséure anhydrids,” Ztschr. anal. Chem., 37, 209 (1898); J. Chem. 
Soc., 74, II, 404 (1898). 


38 CHEMICAL REAGENTS 


ACID SUPPHURIC,;, FUMING 
xHSO. + ySOs. 


I 
ACID SULPHURIC, FUMING. FREE FROM NITROGEN 


A colorless, oily liquid, fuming in the air, and containing 
8 to 10 per cent of free SO, (7.e., 83.1 to 83.5 per cent total 
SO,). 

TESTS OF PURITY 

Non-volatile Matter. — 3 cc. of fuming sulphuric acid, on 
being evaporated and ignited, should leave no weighable 
residue. 

Nitric Acid. — Dilute 1 cc. of fuming sulphuric with 9 ce. 
of water, and overlay the fluid on 5 cc. of diphenylamine 
solution (see Diphenylamine, page 100). No blue zone should 
form at the contact-surfaces of the two liquids. 

Ammonium Salts. — Carefully add 2 ce. of fuming sulphuric 

acid, by drops, to 30 cc. of water, and add aqueous solution 
(1:6) of potassium hydroxide to alkalinity; on now adding 
10 to 15 drops of Nessler’s reagent, at most a pale-yellow, 
but in no case a brownish-red, color or precipitate may 
develop. 
_ Halogens. — Add 1 ce. of fuming sulphuric acid, by drops, 
to 30 cc. of water; on now adding a few drops of silver nitrate 
solution, the liquid must not acquire more than a faint 
opalescent turbidity. ; 

Lead. — On cautiously adding 10 cc. of fuming sulphuric 
acid, by drops, to 50 ec. of 85 per cent alcohol, a clear liquid 
should result, which should contain no precipitate of lead 
sulphate after standing two hours. 

Arsenic.— A Marsh apparatus is set in operation, using 
20 gm. of arsenic-free, granulated zinc, and arsenic-free, 


CHEMICAL REAGENTS 39 


dilute (1:5) sulphuric acid. As soon as the air has been 
expelled from the apparatus, heat the reduction tube to 
redness, then run into the apparatus a cooled mixture of 
10 ce. of the fuming sulphuric acid with 90 cc. of water. 
No deposit of arsenic should be visible in the reduction tube 
within half an hour. 

Quantitative Determination.* — Weigh off accurately 1 gm. 
of fuming sulphuric acid in a Lunge-Rey stoppered bulb 
pipette,t and cautiously allow the acid to*run into 10 ce. 
of water, contained in a porcelain dish. The contents of 
the dish are now rinsed into a measuring flask of 100 ce. 
capacity, and the flask then filled up with water to the 
mark. After vigorously shaking, 25 cc. of the liquid are 
titrated with fifth normal potassium hydroxide solution, 
using methyl orange as indicator. 

1 ce. of fifth normal KOH = 0.008006 gm. of SO,, log. 
90342. 

II 


ACID SULPHURIC, FUMING § 


An oily liquid, sometimes slightly colored, and often not 
perfectly clear. The acid fumes in the air, contains from 


* In accurate determinations, the acidity due to sulphurous acid must 
be deducted from that determined by titration. Regarding this, see 
Lunge, Chem.-tech., Untersuch.-Meth., 5 ed., 1, 395 (1904); J. Chem. Soc., 
68, II, 413 (1895). 

+See Lunge, Chem.-tech. Untersuch.-Meth., 5 ed., 1, 394 (1904); 
illustrated in Trade Catalogues of glassware, etc. 

t In order to ascertain the free SO; from the total SO; found by analysis, 
see the table in Lunge, Chem.-tech. Untersuch.-Meth., 5 ed., 1, 399 (1904); 
compare Thorpe’s Dict. of Appld. Chem., 2 ed., 3, 711 (1895). 

{| This acid, which contains traces of nitric acid, is considerably cheaper 
than the foregoing acid, which is perfectly free from nitrogen. It is well 
adapted for use in laboratories where fuming sulphuric acid is very fre- 
quently used for the Kjeldahl nitrogen determinations. For accurate 
nitrogen determinations, however, it will be necessary to determine the 
nitrogen content of the acid by a blank test carried out in the manner 
above described. 


40 CHEMICAL REAGENTS 


8 to 10 per cent of free SO,, and is intended for nitrogen 
determinations by the Kjeldahl method. 


TESTS OF PURITY 


Nitrogen. — Dilute 30 cc. of the fuming sulphuric acid in 
a retort with 200 cc. of water, and when cold add nitrogen- 
free solution of sodium hydroxide (sp. gr. 1.3), until strongly 
alkaline. Then add 3 gm. of zine dust, distil off about 
50 cc., and collect the distillate in a U-tube receiver con- 
taining about 10 cc. of water and 2 to 3 ce. of fifth normal 
hydrochloric acid. The distillate is then tittated with fifth 
normal potassium hydroxide solution, using methyl orange 
as indicator. The ammonia should not have consumed more 
than 0.2 cc. of the fifth normal hydrochloric acid. 

Quantitative Determination.— The determination is car- 
ried out as described under Acid Sulphuric, Fuming, free 
from nitrogen. 


ACID SULPHURIC, WITH PHOSPHORIC ANHYDRIDE 
APPROXIMATELY 10, 15, on 20% P.O, 


Sulphuric acid containing -phosphorus pentoxide. Approx- 
imately 10, 15, or 20 per cent of P,O, are the usual strengths. 
The preparation is employed in Kjeldahl’s nitrogen determi- 
nation. 


TESTS OF PURITY 


Nitric Acid. — Dilute 1 ce. of the solution of phosphoric 
anhydride in sulphuric acid with 9 ce. of water, and overlay 
this fluid on 5 ec. of diphenylamine solution (see Dipheny- 
lamine, page 100). No blue zone should form at the contact- 
surfaces of the two liquids. 

Ammonium Salts. — Dilute 2 cc. of the solution of phos- 
phorie anhydride in sulphuric acid with 30 cc. of water, and 
add aqueous solution of potassium hydroxide (1:6) to alka- 


CHEMICAL REAGENTS 41 


linity, followed by 10 to 15 drops of Nessler’s reagent. At 
most only a faint yellow, but in no case a brownish-red, 
color or precipitate should form. 


ACID SULPHURIC, FUMING, WITH PHOSPHORIC AN- 
- HYDRIDE 


APPROXIMATELY 5, 10, 15, 20, or 25% P.O, 


Fuming sulphuric acid containing phosphorus pentoxide; 
the usual grades contain approximately 5, 10, 15, 20, or 25 
per cent of P,O,. The preparation is used in Kjeldahl’s 
nitrogen determination. 


TEST OF PURITY 


Nitrogen. — The nitrogen determination is carried .out as 
described under Acid Sulphuric, Fuming. See footnote there. 


ACID SULPHUROUS 
SO. + Aq. Mol. Wt. 64.06. 


A clear, colorless liquid of specific gravity 1.029 to 1.035. 
The acid first reddens blue litmus paper, and then bleaches 
it. The liquid contains about 6 per cent of SO,. | 


TESTS OF PURITY 


Non-volatile Matter. — 10 cc. of sulphurous acid, on being 
evaporated and ignited, should leave no weighable residue. 

Quantitative Determination. — Weigh off 10 gm. of sul- 
phurous acid in a measuring flask of 100 cc. capacity, and 
fill with boiled water up to the mark. Allow the fluid to 
run from a burette into 30 cc. of decinormal iodine solution, 
constantly shaken, until decoloration ensues. To effect this 
not more than 16.2 cc. of the acid solution should be required. 

1 ec. of decinormal I = 0.003203 gm. of SO,, log. 50556. 


42 CHEMICAL REAGENTS 


CUBES FOR GENERATING SULPHUROUS ACID 


Cube-like pieces, containing at least 20 per cent of sul- 
phurous acid. © 


TEST OF STRENGTH 


Quantitative Determination. — Introduce 1 gm. of the finely 
powdered cubes and 5 gm. of anhydrous sodium carbonate 
into a graduated flask of 100 cc. capacity; add 50 cc. of 
water, boil the mixture for about ten minutes, allow to cool, 
fill the flask up to the mark, and filter. Run the filtrate 
from a burette into a constantly shaken mixture of 30 cc. 
of decinormal iodine solution and 10 ec. of hydrochloric acid, 
until complete decoloration ensues. 

1 cc. of decinormal I = 0.003203 gm. of SO,, log. 50556. 


ACID TANNIC 


(TANNIN) 
Ci4H00o. Mol. Wt. 322.08. 


A yellowish powder, or crystal-like, lustrous scales. Tannic 
acid is soluble in 5 parts of water and in 2 parts of 85 per 
cent alcohol, yielding a clear liquid acid to litmus paper. 
Tannic acid is also soluble in about 8 parts of glycerin but 
is almost insoluble in ether. 


TESTS OF PURITY 


Inorganic Matter.—1 gm. of tannin on ignition should ° 
not leave a residue exceeding 0.002 gm. in weight. 

Sugar, Dextrin. — On mixing 10 cc. of an aqueous (1:5) 
solution of tannic acid with 10 ec. of 85 per cent alcohol, 
the mixture must remain clear for one hour; nor should a 
turbidity occur on the further addition of 5 cc. of ether. 


CHEMICAL REAGENTS 43 


Water. — On drying tannic acid at 100° C., it should not 
lose more than 12 per cent of its weight. 

Nors. — Regarding the quantitative determination of tannic acid, see 
Fresenius, Anleitung zur quantitativen Analyse, Vol. II, 619 [or Lunge, 


Chem.-tech. Untersuch.-Meth., 4 ed., 3, 560 ff. (1900)]; Fresenius-Cohn 
Quantitative Analysis, Vol. II, 767 ff. (1904). 


ACID TARTARIC 
CsH.Oc. Mol. Wt. 150.04. 

Colorless, prismatic crystals, or crystalline crusts, soluble 
in 0.8 part of water, and in 2.5 parts of 85 per cent 
alcohol. 

TESTS OF PURITY 


Sulphuric and Oxalic Acids, and Calcium. — Separate 20.cc. 
portions of the aqueous (1:10) solution of the acid should 
show no change with barium chloride nor ammonium oxalate 
solutions; nor, when lowered to slight acidity by adding 
ammonia water, should a precipitate be obtained on adding 
calcium sulphate solution. 

Lead and other Metals. — 

(a) The solution of 5 gm. of tartaric acid in 20 ce. of 

water, with 12 cc. of ammonia water added, should 
not. develop a brown color on the addition of hy- 
drogen sulphide water. 

(b) 20 ec. of the 1:10 aqueous solution should not be 

affected by hydrogen sulphide water. 

Inorganic Matter.—1 gm. of tartaric acid, on being ignited, 
should leave no weighable residue. 

Quantitative Determination. — Dissolve 1 gm. of tartaric 
acid in 50 ec. of water, and titrate with normal sodium 
hydroxide solution, using phenolphthalein as indicator. 

1 ce. of normal NaOH = 0.07502 gm. of C,H,O,, log. 87518. 


44 CHEMICAL REAGENTS 


ACID THIOACETIC 
CH;COSH. Mol. Wt. 76.09. 

A yellow liquid of penetrating odor, boiling between 92 
and 97° C., and having a specific gravity of 1.070. Thioacetic 
acid is soluble in 16 parts of water, and easily -in alcohol. 
The 6 per cent aqueous solution is used instead of hydrogen 
sulphide in chemical analysis.* 


TESTS OF PURITY 


Non-volatile Matter. — 10 cc. of thioacetic acid, on being 
evaporated and ignited, should leave no weighable residue. 

Sulphuric Acid. — On dissolving 5 ec. of thioacetie acid in 
100 cc. of water, and adding barium chloride solution, no 
turbidity should occur, nor should a precipitate form. 


ALCOHOL ETHYLIC 
C.H;s-OH. Mol. Wt. 46.04. 


I 


ALCOHOL ABSOLUTE 


A clear, colorless liquid of specific gravity 0.796 to 0.798 
(99 to 99.6 per cent by weight), and boiling at 78.5° C. 
Alcohol should not affect litmus paper. 


TESTS OF PURITY 


Residue. — 50 cc. of alcohol, on being slowly evaporated, 
should leave no residue. 


* Regarding the use of thioacetic acid, see the following: R. Schiff and 
N. P. Tarugi, Ber., 27, 3437 (1894) [or Ztschr. anal. Chem., 34, 456 (1895)]; 
J. Chem. Soc., 68, II, 84 (1895). R. Schiff, Ber., 28, 1204 (1895); J. 
Chem. Soc., 68, II, 370 (1895). 


CHEMICAL REAGENTS 45 


Fusel Oil.* — On mixing 10 cc. of alcohol and 30 ce. of 
water in an Erlenmeyer flask, no turbidity or coloration 
- should be observed, nor should any foreign odor be noticeable. 

A mixture of 10 cc. of alcohol and 0.20 ce. of 15 per cent 
sodium hydroxide solution, when evaporated down to 1 ce. 
and supersaturated with dilute sulphuric acid, should not 
have the odor of fusel oil. 

On rubbing a few drops of alcohol between the hands, no 
unpleasant odor should be noticeable. 

Molasses-Alcohol. — On overlaying 5 ce. of aleohol on 5 ce. 
of concentrated sulphuric acid, no rose-red zone should form 
within one hour at the contact-surfaces of the two liquids. 

Aldehyde. — On warming 10 ce. of alcohol with 5 drops of 
silver nitrate solution and 1 cc. of water for ten minutes on 
the water-bath (70 to 80° C.), neither a turbidity nor a 
precipitate should form. : | 

Organic Impurities. — The red color of a mixture of 10 cc. 
of alcohol and 1 drop of a 1: 1000 potassium permanganate 
solution should not pass into yellow within twenty minutes. 

Metals and Tannin. — On adding to 10 ce. of alcohol 1 ce. 
of ammonia water or 5 ec. of hydrogen sulphide water, 
no coloration should develop. 


* Regarding the quantitative determination of fusel oil, see Lunge, 
Chem.-tech. Untersuch.-Meth., 4 ed., 3, 422, 442 (1900); Allen, Com. 
Organ. Anal., 3 ed., Vol. I, p. 167 ff. (1898). A. Stutzer and O. Reitmaier, 
Ztschr. angew. Chem., 3, 522 (1890); J. Chem. Soc., 60, 622 (1891). G. 
Lunge, V. Meyer, and E. Schulze, Chem. Centralb. (3), 15, 854 (1884); 
_ J. Chem. Soc., 48, 708 (1885). M. Glasenapp, Ztschr. angew. Chem., 8, 
657 (1895); J. Chem. Soc., 70, II, 277 (1896). H. Borntrager, Chem. 
Ztg., 18, Rep. p. 27 (1889); compare J. Chem. Soc., 56, 552 (1889), and 
58, 669 (1890). See also Ztschr. Spiritusind., 1886, 362. 

+A partial decolorization of potassium permanganate occurs even 
with the purest alcohol. Compare also M. E. Barbet, J. Pharm. Chim., 
19, 413, 457 (1889) [or Pharm. Ztg., 34, 481 (1889)]. P. Cazeneuve, 
Chem. Ztg., 18, Rep. p. 198 (1889); for similar article see J. Chem. Soc., 
56, 928 (1889). Lang, Chem. Ztg., 17, 1544 (1893). . 


46 CHEMICAL REAGENTS 


II 
ALCOHOL, 95% 


A clear, colorless liquid of about 0.816 specific gravity 
(15.6° C.), and containing about 95 per cent by volume of 
absolute alcohol, C,H,OH. It boils at 78° C., is miscible in 
all proportions with water, and does not change the color of 
moistened litmus paper. 


TESTS OF PURITY 


Residue. — 50 cc. of alcohol, on being slowly evaporated, 
should leave no weighable residue. 

Fusel Oil. — Mix 10 cc. of alcohol, 5 cc. of water, and 1 ce. 
of glycerin, saturate a piece of clean, odorless blotting-paper 
with the mixture, and allow to evaporate spontaneously. 
No foreign odor should be noticeable after the evaporation. 

Aldehyde, Tannin. — 10 cc. of alcohol mixed with 5 cc. of 
potassium hydroxide solution (5%) should not become yellow 
at once. 

Foreign Organic Matter, Aldehyde, etc. — Shake 20 cc. of 
alcohol with 1 ce. of decinormal silver nitrate solution. Not 
more than a faint opalescence should appear, nor more than 
a faint brownish tint after exposing for six hours to diffused 
daylight. 

Furfural.— Add ten drops of aniline and two or three 
drops of hydrochloric acid to 10 ce. of alcohol. No pinkish- 
red color should appear. 


III 
ALCOHOL, 85% 


This alcohol has a specific gravity of 0.830 to 0.834, and 
contains 87.2 to 85.6 per cent of alcohol, C,H,OH, by weight. 


In other respects it conforms to the requirements given under 
Alcohol Absolute. 


CHEMICAL REAGENTS 47 


ALCOBROE ARM YLIC 
CsHiu : OH. Mol. Wt. 88.07: 


I ; 
AMYL ALCOHOL 


A clear, colorless liquid, neutral to litmus paper. Amyl — 
alcohol is but slightly soluble in water, but is clearly miscible 
with alcohol, ether, and benzin. It has a specific gravity 
of 0.814 and boils at 131° C. 


TESTS OF PURITY 


Non-volatile Matter. — 10 gm. of amyl alcohol evaporated 

on the water-bath should leave no weighable residue. 

Foreign Organic Matter (Furfural, etc.). — 

(a) On shaking 5 ce. of amyl alcohol with 5 cc. of con- 
centrated sulphuric acid, the mixture should not 
acquire more than a faint yellow or reddish color. 

(b) On shaking 5 ec. of amyl alcohol with 5 cc. of potas- 
sium hydroxide solution, the amyl alcohol should 
not acquire any color. | 


II 


AMYL ALCOHOL FOR GERBER’S FAT DETERMI- 
NATION 


A colorless liquid boiling at 128 to 130° C., and of specific 


gravity 0.815. 
TEST OF PURITY 


1 ec. of amyl alcohol shaken with 10 cc. of concentrated 
sulphuric acid, and 11 cc. of water in a Gerber butyrometer, 
then centrifuged for two or three minutes, and then allowed 
to stand for twenty-four hours, must not exhibit an oily 
portion.* | 


* Compare N. Gerber and M. M. Craandijk, Milch Ztg., 27, 611 (1898). 
Chem. Centralb., [5], 2, II, 907 (1898). 





SF THE 


OF 


‘LIFORNIEs 





—_— 


48 _ CHEMICAL REAGENTS 


ALCOHOL METHYLIC 
CH;:OH. Mol. Wt. 32.03. 


A colorless, mobile liquid, readily miscible in all propor- 
tions with water, alcohol, ether, and fatty and volatile oils. 
Methyl alcohol has the specific gravity 0.796, and boils 
between 65 and 66° C. It should not redden blue litmus 
paper. 

TESTS OF PURITY 


Non-volatile Matter. — 30 cc. of methyl alcohol evaporated 
on the water-bath should leave no weighable residue. 

Acetone and Ethyl Alcohol. — Shake together thoroughly 
50 ec. of double normal sodium hydroxide solution and 5 ce. 
of methyl alcohol in a mixing, cylinder, and add, with repeated 
shaking, 25 cc. of double normal iodine solution. ‘No tur- 
bidity or flocculent precipitate should occur; nor should an 
odor of iodoform be perceptible. 

Empyreumatic Substances. — 1 cc. of methyl alcohol should 
dissolve without turbidity in 10 cc. of water. On allowing 
5 ec. of concentrated sulphuric acid to drop into 5 ce. of 
methyl alcohol while kept cold, the mixture should not 
acquire more than a slightly yellowish color. 

Aldehydes. — On shaking 10 cc. of methyl alcohol with 
10 ec. of sodium hydroxide solution (sp. gr. 1.8), the mixture 
should remain colorless, j 

Substances Oxidizable by Permanganate.— On adding 1 
drop of decinormal potassium permanganate solution to 10 ce. 
of methyl alcohol, the red color of the liquid must not disap- 
pear within ten minutes. 


Nortr. — Regarding the quantitative determination of methyl alcohol, 
as well as the quantitative determination of acetone in methyl alcohol, see 
Lunge, Chem.-tech. Untersuch.-Meth., 4 ed., 3, 693 (1900); compare 
G. Kramer, H. Strache, and J. Messinger as given in note under Acetone, 


Peds 


CHEMICAL REAGENTS 49 


ALPHANAPHTHOL 
CioH7-OH. Mol. Wt. 144.06. 

Colorless, lustrous needles, having a phenolic odor, and 
melting at 95° C. Alphanaphthol is difficultly soluble in 
cold water, more readily soluble in warm water, and dissolves 
easily in alcohol, ether, benzene, and chloroform. 


TESTS OF PURITY 


Inorganic Matter.—1 gm. of alphanaphthol ignited on 
platinum foil should leave no weighable residue. 

Organic Acids. — On shaking 1 gm. of alphanaphthol with 
100 cc. of water and filtering, the filtrate should not redden 
blue litmus paper. 


ALUMINUM OXIDE 
Al.O3. Mol. Wt. 102.2. 


A white, very bulky, hygroscopic powder,* used for Wis- 
licenus’ ¢ determination of tannin. Under a microscope, mag- 
nifying about 30 to 60 diameters, the powder appears in the 
form of partly transparent, flocculent masses, resembling 
vegetable tissue. 


TESTS OF PURITY 


Metallic Mercury and Aluminum.— On moistening the 
preparation with water or alcohol, it acquires a gray color 
if any aluminum or mercury is present; if pure, it remains 
perfectly white. No globules of mercury or particles’ of 
metallic aluminum should be visible under the microscope. 

Absorptive Power for Tannin.—1 gm. of freshly ignited 


* The preparation must always be ignited before using in a determi- * 
nation of tannin. 

+H. Wislicenus, Determination of Tannin Without Hide Powder, 
Ztschr. angew. Chem., 17, 801 (1904); J. Soc. Chem. Ind., 28, 765 (1904). 
Ztschr. anal. Chem., 44, 96 (1905); J. Chem. Soc., 88, II, 363 (1905). 


50. CHEMICAL REAGENTS 


aluminum oxide is vigorously shaken for five minutes with 
200 ce. of a solution of 4.5 gm. of pure tannin in sufficient 
water to make 1000 cc. (Use a flask with a rubber stopper.) 
The mixture is then heated for five minutes on the water- 
bath, and filtered. 50 cc. of the filtrate are evaporated in a 
weighed platinum or nickel dish, and the residue dried at 
105° C. and weighed. 

The total residue obtained from 50 cc. of the original 
tannin solution, and dried at 105° C., is also ascertained. 
On now calculating the residue for 200 cc. of tannin solution, 
and deducting this from the total residue left from the tannin 
solution treated with the aluminum oxide, the result should 
show that 1 gm. of aluminum oxide absorbs 0.40 to 0.50 gm. 
of tannin. 

AMMONIA WATER 
NH; + H.O. Mol. Wt. NH; = 17.06. 

The aqueous solution of ammonia gas is a clear, colorless 
liquid, the specific gravity of which decreases as the ammonia 
content increases. 

For analytical purposes, two solutions of different concen- 
tration are ordinarily used, of which one has a specific gravity 
of about 0.96, and contains about 10 per cent of NH,, while 
the other, the concentrated, has the specific gravity of about 
0.925, and contains about 20 per cent of NH,. In American 
laboratories a still more concentrated solution of ammonia 
is employed. Its strength is about 28 per cent and it is 
_ generally designated as ‘Stronger Ammonia Water.” 


I 
AMMONIA WATER, 28% 


(STRONGER AMMONIA WATER) 


A clear, colorless liquid having a specific gravity of about 
0.90, and containing about 28 per cent of NH. 


CHEMICAL REAGENTS 51 


TESTS OF PURITY 


Non-volatile Matter. — On evaporating 3.5 cc. of the am- 
monia water on the water-bath, no weighable residue should 
remain. A trace of residue, however, is almost always left. 

Chlorides; Pyridine. — Dilute 3.5 cc. of the ammonia water 
with 30 cc. of water, and supersaturate with 20 cc. of nitric 
acid. The solution should remain colorless. This liquid 
should show no change on the addition of silver nitrate solu- 
tion. 

Heavy Metals. — On diluting 2 cc. of the ammonia water 
with 20 cc. of water, and then adding a few drops of ammo- 
nium sulphide solution, no change should appear. - 

Sulphates. — Slightly acidify 3.5 cc. of the ammonia water 
with hydrochloric acid, and add barium chloride solution. 
No precipitate of barium sulphate should form on standing 
twelve hours. ; 

Carbon Dioxide. — 3.5 cc. of the ammonia water with 
15 cc. of calcium hydroxide solution should not at once 
become more than slightly opalescent. 

Quantitative Determination. — Dilute 2 gm. of the am- 
monia water with about 50 cc. of water, and titrate with 
normal hydrochloric acid, using methyl orange indicator. 

1 cc. of normal HCl = 0.01706 gm. of NH,, log. 23198. 


II 
AMMONIA WATER, 20% 
(CONCENTRATED AMMONIA WATER) 


This solution of ammonia has the specific gravity 0.925 and 
contains about 20 per cent of NH. 
| TESTS OF PURITY 


The tests for non-volatile matter, chlorides, pyridine, heavy 
metals, sulphates, and per cent of NH, as described under 


52 CHEMICAL REAGENTS 


Ammonia Water 28 per cent, are to be made. But, instead 


_ of 3.5 ec. of the 28 per cent use 5 cc. of the 20 per cent am- 


monia. The preparation should also conform to the following 
tests. | 

Sulphides. — On adding a few drops of an ammoniacal 
lead acetate solution to 5 cc. of the ammonia water, the 
liquid must not acquire a yellow or a brown color, nor should 
a dark precipitate form. 

Tar-Bases (Aniline, Pyridine, Pyrrol, etc.). — Evaporate 
a mixture of 5 cc. of the ammonia water and 20 cc. of nitric. 
acid on the water-bath. The residue on evaporation should 
have a pure white color. 

Calcium. — A mixture of 5 ec. of the ammonia water 
with 20 cc. of water should exhibit no turbidity on the 
addition of ammonium oxalate solution. 

Magnesium. — On adding ammonium phosphate solution 
to 10 cc. of the ammonia water, no precipitate should form 
on standing two hours. 

Carbonates. — 10 cc. of the ammonia water, when mixed 
with 20 cc. of lime water and boiled, should not develop 
more than a very slight turbidity. 

Phosphates. — To 10 cc. of the ammonia water add 40 cc. 
of nitric acid and 25 cc. of ammonium molybdate solution. 


No yellow precipitate should form in the liquid on standing 


two hours at about 40° C. 


II 
AMMONIA WATER, 10% 


This is the article termed ‘‘ammonia water” throughout 
the text of this book. It contains about 10 per cent of NH,, 
and has a specific gravity about 0.96. 


CHEMICAL REAGENTS 53 


TESTS OF PURITY 


The tests of purity and details of execution are the same 
as those given under Ammonia Water, 20 per cent. But, in 
testing this use double the quantities of ammonia water 
employed in testing the 20 per cent. 


AMMONIUM ACETATE 
NH.C2H;O2. Mol. Wt. 77.1. 
A white, hygroscopic, crystalline mass, easily soluble in 
water and in alcohol. 


TESTS OF PURITY 


Non-volatile Matter. — 3 gm. of ammonium acetate, when 
ignited, should leave no weighable residue. 

Chlorides. — The solution of 1 gm. of ammonium acetate 
in 20 ce. of water, acidulated with 5 ce. of nitric acid, should 
show no change on the addition of silver nitrate solution. 

Sulphates. — On adding 1 cc. of hydrochloric. acid to a 


solution of 1 gm. of ammonium acetate in 20 ce. of water, 


followed by barium chloride solution, no precipitate of 
barium sulphate should form on standing twelve hours. — 

Heavy Metals and Earths. — The solution of 5 gm. of 
ammonium acetate in 100 cc. of water should not be affected 
by hydrogen sulphide water. Furthermore, the addition of 
ammonia water and ammonium oxalate solution should 
cause neither a coloration nor a turbidity. 


AMMONIUM CARBONATE 
(NH.)HCO; - (NH,)NH:CO:. 

The term ‘‘ammonium carbonate” is generally applied to 
a mixture of ammonium bicarbonate and carbamate, forming 
a crystalline, white, translucent mass which readily effloresces, 
becomes opaque, and gives off an odor of ammonia. 


54. CHEMICAL REAGENTS 


TESTS OF PURITY 
_ Non-volatile Matter.—5 gm. of ammonium carbonate, 
when ignited, should leave no weighable residue. 

Sulphates. — Dissolve 5 gm. of ammonium carbonate in 
100 cc. of water and 10 cc. of hydrochloric acid, heat the 
solution to boiling, and add barium chloride solution. No 
precipitate of barium sulphate should form on standing 
twelve hours. 

Chlorides and Thiosulphates. — The solution of 2 gm. of 
ammonium carbonate in 50 ce. of water should not be affected 
on adding 10 ce. of nitric acid, followed by silver nitrate 
solution. 

Heavy Metals. — To a solution of 5 gm. of ammonium 
carbonate in 30 ec. of water is added 30 cc. of dilute acetic 
acid, then 20 ce. of ammonia water, then a few drops of 
ammonium sulphide solution. No precipitate should form, 
nor should the liquid acquire a green or a brown color. 

Sulphocyanates. — The solution of 1 gm. of ammonium 
carbonate in 20 cc. of water and 2 cc. of hydrochloric acid 
should not be reddened on adding 1 drop of ferric chloride | 
solution. 

Tar Bases. — Acidify 1 gm. of ammonium carbonate with 
5 ec. of nitric acid, and evaporate the solution to dryness on 
the water-bath. The residue must have a pure white color. 


AMMONIUM CHLORIDE 
NH.CI. Mol. Wt. 53.52. 
A white, crystalline powder, easily soluble in water. 


TESTS OF PURITY 


Non-volatile Matter. — 3 gm. of ammonium chloride, when 
gently ignited, should leave no weighable residue. 
Phosphates and Arsenates. — Dissolve 5 gm. of ammonium 


CHEMICAL REAGENTS 55 


chloride in 20 ec. of water, and add to the clear solution 3 ee. 
of magnesia mixture and 10 cc. of ammonia water. No — 
precipitate should form on standing twelve hours. 

Heavy Metals and Earths. — 20 cc. portions of the aqueous 
1: 20 solution of the salt should not be affected by hydrogen 
sulphide water, ammonia water, ammonium sulphide solu- 
tion, and ammonium oxalate solution. 

Sulphates. — On adding to 10 cc. of the 1:10 solution a 
few drops of hydrochloric acid, followed by barium chloride 
solution, no precipitate of barium sulphate should form on 
standing twelve hours. 

Sulphocyanates. — Dissolve 1 gm. of ammonium chloride 
in 10 ec. of water, and add to the solution a few drops of 
hydrochloric acid and 1 drop of ferric chloride solution. 
The liquid should not acquire a red color. 

Tar Bases. — On evaporating to dryness 1 gm. of ammo- 
nium chloride with 5 cc. of nitric acid on the water-bath, 
the residue must have a pure white color. 


AMMONIUM CITRATE SOLUTION 


A clear, colorless liquid, containing 150 gm. of pure, crys- 
tallized citric acid and 23 gm. of ammonia-nitrogen (= 27.93 
gm. of NH;) per liter. The solution has an acid reaction to 
litmus paper and is used for determining citrate-soluble phos- 
phoric acid in Thomas slag, by the method of Wagner. 


TEST FOR PROPER CONTENT OF AMMONIA-NITROGEN 


Dilute 25 cc. of the ammonium citrate solution with water 
to 250 ce. To 25 cc. of this diluted solution add 3 gm. of 
calcined magnesia and about 200 cc. of water, and distil, 
using a receiver containing 40 cc. of semi-normal sulphuric 
acid. After the distillation titrate the excess of acid with 


56 CHEMICAL REAGENTS 


semi-normal potassium hydroxide solution, using methyl 
orange as indicator. 

1 ce. of semi-normal H,SO, = 0.00702 gm. of N (log. 8463) 
= 0.00853 gm. of NH,, log. 9309. 


AMMONIUM DITHIOCARBONATE SOLUTION 
CO(SNH,),. Mol. Wt. 128.26. 


A yellow liquid of ammoniacal odor, and containing about 
10 to 12 per cent of ammonium dithiocarbonate, about 8 per 
cent of ammonium chloride, and small quantities of ammo- 
nium sulphocyanate and ammonium sulphide. It is used as 
a substitute for hydrogen sulphide and ammonium sulphide. 


TESTS OF PURITY 


Non-volatile Matter. — 10 cc. of ammonium dithiocarbonate 
solution, on being evaporated and ignited, should leave no 
weighable residue. 

Ammonium Carbonate. — On adding 3 cc. of calcium chlo- 
ride solution to 10 ce. of the ammonium dithiocarbonate so- 
lution, no precipitate should form, even on warming. 

Notr. — Regarding the employment of ammonium dithiocarbonate, 


see M. Vogtherr, Ber. d. pharm. Ges., 8, 232 (1898) [or Pharm. Centrhl., 
39, 692 (1898)]; J. Chem. Soc., 78, II, 241 (1900). 


AMMONIUM FLUORIDE 
NH,F. Mol. Wt. 37.07. 
White crystals, easily soluble in water, affording a solution 
which usually exhibits an acid reaction because of the pres- 
ence of NH,F-HF. 
TESTS OF PURITY 


Non-volatile Matter.— 10 gm. of ammonium fluoride on 
ignition should leave no weighable residue. 
Chlorides. — On dissolving 5 gm. of ammonium fluoride in 


CHEMICAL REAGENTS 57 


25 cc. of water, and adding a few drops of nitric acid, followed 
by silver nitrate solution, the liquid must exhibit no change. 

Sulphates and Silicofluorides. — Dissolve 5 gm. of ammo- 
nium fluoride in a platinum dish in 25 ec. of water, and add 
25 cc. of hydrochloric acid, followed by barium chloride 
solution. No turbidity should ensue. 

Heavy Metals. — Dissolve 5 gm. of ammonium fluoride in 
25 cc. of water, add to the solution a few drops of hydro- 
chloric acid, and 10 cc. of hydrogen sulphide water. No 
change should appear. Now add ammonia water to alka- 
linity, and a few drops of ammonium sulphide solution; at 
most a slight greenish coloration may develop, but a precipi- 
tate should not form. 


AMMONIUM MOLYBDATE 
(NH,z)6Mo7O24 + 4H:O. Mol. Wt. 1236.43. 


Large, colorless, or slightly greenish crystals, soluble in 
water, which, when heated, liberate ammonia and water, 
leaving molybdic anhydride. 


TESTS OF PURITY 


Phosphates. — 10 gm. of ammonium molybdate with 25 ce. 
of water and 15 cc. of ammonia water (sp. gr. 0.910) should 
afford a clear solution. Add this solution to 150 cc. of 
nitric acid (sp. gr. 1.20*). No yellow precipitate should 
form on standing two hours at a temperature of about 40° C. 

Heavy Metals. — Dissolve 2 gm. of ammonium molybdate 
in 5 ce. of water and 5 cc. of ammonia water, and to the 
solution add 10 ec. of hydrogen sulphide water. Neither a 
green coloration nor a precipitate should form. 

Sulphates. — On dissolving 1 gm. of ammonium molybdate 


* The ammonium molybdate solution should be added to the nitric 
acid gradually and with constant rotation; never otherwise. 


08 CHEMICAL REAGENTS 


in 10 ec. of water, and acidifying the solution with nitric acid, 
no change should be observed on the further addition of 
barium nitrate solution. 

Chlorides. — 20 ce. of the 1:10 aqueous solution acidified 
with nitric acid should show no change on the addition of — 
silver nitrate solution. 

Quantitative Determination.— The content of molybdic 
anhydride may be approximately determined by gently 
igniting about 1 gm. of the salt until the ammoniacal odor 
has disappeared, and then weighing the residue of molybdic 
anhydride; it should amount to about 81 per cent. The 
accurate determination is carried out in the manner described 
under Acid Molybdic Anhydride, on page 19. 


AMMONIUM NITRATE 
NH«NOs;. Mol. Wt. 80.11. 


Colorless crystals easily soluble in water. 


TESTS OF PURITY 


The tests to be made are those described under ammonium 
chloride; and, in addition, tests for chlorides and nitrites. 

Chlorides. — On dissolving 1 gm. of ammonium nitrate in 
10 cc. of water, and adding a few drops of nitric acid, followed 
by silver nitrate solution, the liquid should remain unchanged. 

Nitrites. — To the solution of 1 gm. of ammonium nitrate 
in 20 ce. of water are added 1 cc. of 16 per cent sulphuric 
acid and 1 cc. of a freshly prepared (0.5:100*) colorless 
solution of metaphenylenediamine hydrochloride: no yellow 
or yellowish-brown color should develop. 

* Should the solution of metaphenylenediamine hydrochloride already 


have a color it is to be decolorized before use by warming with ignited 
animal charcoal. 


CHEMICAL REAGENTS 59 


AMMONIUM OXALATE 
(NHa4)2C20.4 + H.0. Mol. Wt. 142.16. 


Colorless crystals, clearly soluble in 25 parts of cold water. 
The aqueous solution should be neutral to litmus paper. 


TESTS OF PURITY 


Non-volatile Matter.— 3 gm. of ammonium oxalate on 
ignition should leave no weighable residue. 

Sulphates. — Dissolve 5 gm. of ammonium oxalate in 
200 cc. of water, heat the solution to boiling, and then add 
10 ec. of hydrochloric acid, followed by barium chloride 
solution. No precipitate of barium sulphate should form on 
standing twelve hours. 

Chlorides. — On adding to a solution of 1 gm. of ammo- 
nium oxalate in 25 cc. of water, 10 cc. of nitric acid, and a 
few drops of silver nitrate solution, no turbidity should 
develop on shaking. 

Heavy Metals.— To a solution of t gm. of ammonium 
oxalate in 25 ec. of water add hydrogen sulphide water; the 
solution should remain unchanged. Now add to the liquid 
5 cc. of ammonia water; no green color should develop, nor 
should a precipitate form. 

Quantitative Determination. — This is to be made as de- 
scribed under Potassium Oxalate Neutral on page 178. 

~1 ce. of decinormal KMnO, = 0.007108 gm. of (NH,). 
C0, + H,0, log. 85175. 


AMMONIUM PHOSPHATE 
(NH4)2HPOs,. Mol. Wt. 132.15. 


Colorless crystals, or white, crystalline powder, soluble in 
4 parts of cold, or 0.5 part of boiling, water. The aqueous 
solution is slightly alkaline to litmus paper. 


60 CHEMICAL REAGENTS 


TESTS OF PURITY 


Alkalies. — The solution of 2 gm. of ammonium phosphate 
in 100 cc. of water is treated with lead acetate solution in 
slight excess to precipitate the phosphoric acid, and is then 
filtered. The excess of lead in the filtrate is then precipitated 
with hydrogen sulphide, the liquid filtered, the filtrate evap- 
orated to dryness, and the residue ignited. The residue 
should not be soluble in water, nor should it have an alkaline 
reaction. 

Arsenic. — On shaking 1 gm. of powdered ammonium 
phosphate with 3 cc. of stannous chloride solution, the 
mixture should not darken within one hour. 

Carbonates and Sulphates. — On -adding hydrochloric acid 
to a solution of 1 gm. of ammonium phosphate in 20 cc. of 
water, no effervescence should take place; and on adding 
barium chloride solution, no precipitate of barium sulphate 
should form on standing twelve hours. 

Chlorides. — On dissolving 1 gm. of ammonium phosphate 
in 20 ec. of water, and adding 5 ee. of nitric acid, followed by 
silver nitrate solution, not more than a very slight opalescence 
should develop. 

Nitrates. — Dissolve 2 gm. of ammonium phosphate in 
10 ec. of water, and to the solution add 1 drop of indigo 
solution (1: 1000), followed by 10 cc. of concentrated sul- 
phurie acid. The liquid should still retain its blue color on 
standing one hour. 

Heavy Metals. — On dissolving 2 gm. of ammonium phos- 
phate in 20 ec. of water, acidifying the solution with hydro- 
chloric acid, and then adding hydrogen sulphide water, no 
change should be seen. On now rendering the liquid alkaline 
with ammonia water, and adding a few drops of ammonium 
sulphide solution, no green color should develop, nor should 
a precipitate form. 


CHEMICAL REAGENTS 61 


AMMONIUM SULPHATE 
(N H,)2SOs,. Mol. Wt. 132.14. 


Colorless crystals, soluble in 2 parts of cold, and in 1 part 
of boiling, water; insoluble in alcohol. 


TESTS OF PURITY 


Non-volatile Matter. — 3 gm. of ammonium sulphate on 
ignition should leave no weighable residue. 

Chlorides. — The solution of 2 gm. of ammonium sulphate 
in 20 cc. of water should not become turbid on acidifying 
with nitric acid and then adding silver nitrate solution. 

Heavy Metals. — The solution of 2 gm. of ammonium 
sulphate in 20 cc. of water should remain unaffected by 
hydrogen sulphide, and by ammonia water with ammonium 
sulphide solution. : 

- Sulphocyanates. — Dissolve 1 gm. of ammonium sulphate 
in 10 ce. of water; on adding to the solution several drops of 
hydrochloric acid and 1 drop of ferric chloric solution, the 
liquid should not acquire a red color. 

Phosphates and Arsenates. — Dissolve 5 gm. of ammonium 
sulphate in 20 cc. of water, and add to the clear solution 
3. cc. of magnesia mixture and 10 cc. of ammonia water. 
No precipitate should form on standing twelve hours. 

Nitrates. — Dissolve 2 gm. of ammonium sulphate in 10 ce. 
of water, and add to the solution 1 drop of indigo solution 
(1: 1000), followed by 10 cc. of concentrated sulphuric acid. 
The liquid should still retain its blue color on standing one 
hour. 


AMMONIUM SULPHOCYANATE 
(AMMONIUM THIOCYANATE) 


NH.SCN. Mol. Wt. 76.17. 
Colorless crystals, easily soluble in water and in alcohol. 


62 CHEMICAL REAGENTS 


TESTS OF PURITY 


Non-volatile Matter. — 2 gm. of ammonium sulphocyanate, 
on being ignited, should leave no weighable residue. 

Substances insoluble in Alcohol. —1 gm. of ammonium 
sulphocyanate should completely dissolve in 10 ce. of absolute 
alcohol, and yield a perfectly clear solution. 

Sulphates. — On adding a few drops of hydrochloric acid, 
followed by barium chloride solution, to a solution of 1 gm. 
of ammonium sulphocyanate in 20 ce. of water, no reaction 
should be observed within five minutes. ~ 

Heavy Metals. — On dissolving 1 gm. of ammonium sul- 
phocyanate in 20. cc. of water, and adding to the solution 
several drops of ammonium sulphide solution, no precipitate 
should form, nor should a brown color develop. 

Iron. — The solution of 1 gm. of ammonium sulphocyanate 
in 20 cc. of water should remain perfectly colorless on adding 
0.5 ce. of hydrochloric acid. 


AMMONIUM SULPHIDE SOLUTION 


(AMMONIUM SULPHYDRATE SOLUTION) 


A colorless or yellowish liquid, produced by passing 
hydrogen sulphide into ammonia water. It is strongly 
alkaline towards litmus paper. 


TESTS OF PURITY 


Arsenic, Antimony, and Tin.— On adding hydrochloric 
acid to 50 ec. of ammonium sulphide solution to acidity, 
- hydrogen sulphide gas is liberated in copious amounts, but 
no colored precipitate should form. 

Non-volatile Matter. — On evaporating and igniting 10 ce. 
of ammonium sulphide solution in a porcelain dish, no 
weighable residue should remain. 


CHEMICAL REAGENTS 63 


Ammonium Carbonate.— On adding 3 cc. of calcium 
chloride solution to 10 cc. of ammonium sulphide solution, 
no precipitate should form, even on warming. 


AMMONIUM THIOACETATE SOLUTION 


(ScHIFF’s REAGENT) 
CH;:COSNH,. Mol. Wt. 93.15. 
A clear, yellowish liquid, having a faint odor resembling 
that of ammonium sulphide, and slightly alkaline to litmus 
paper. The solution contains about 30 per cent of ammonium 


thioacetate. 
TESTS OF PURITY 


Non-volatile Matter.— 10 cc. of ammonium thioacetate 
solution on evaporation and ignition should leave no weighable 
residue. 

Ammonium Carbonate.— On adding 3 ec. of calcium 
chloride solution to 10 ec. of ammonium thioacetate solution, 
no precipitate should form, even on warming. 

Sulphates. — A mixture of 10 cc. of ammonium thioacetate 
solution with 10 cc. of diluted acetic acid should not 
immediately be rendered turbid on the addition of barium 
chloride solution. 

Nore. — The reagent can be kept only a short time unchanged; it 
readily becomes turbid. It is, therefore, advantageous to prepare only 
sufficient for eight to ten days’ use, which may be done by dissolving the 
thioacetic acid in a slight excess of ammonia water. 

Regarding the use of ammonium thioacetate solution in analysis, see 
R. Schiff and N. P. Tarugi, Ber., 27, 3437 (1894) [or Ztschr. anal. Chem., 


34, 456 (1895)]; J. Chem. Soc., 68, II, 84 (1895). R. Schiff, Ber., 28, 
1204 (1895); J. Chem. Soc., 68, II, 370 (1895). 


ANILINE 
CoH; . NHsz. Mol. Wt. 93.09. 


A colorless, oily, strongly refractive liquid, which rapidly 
becomes brown on exposure to light and air. 


64 CHEMICAL REAGENTS 


Aniline is soluble in about 35 parts of water. It solidifies 
in a freezing mixture, and then melts at — 8° C. Its 
specific gravity is 1.027; its boiling point, 183° C. 


TESTS OF PURITY 


Hydrocarbons and Nitrobenzene. — 5 cc. of aniline dissolved 
in 10 ce. of hydrochloric acid should form a clear fluid which, 
on being diluted with 15 cc. of water, should not become 
cloudy on cooling. 

Nore. — Regarding the examination of aniline, see Lunge, Chem.-tech. 
Untersuch.-Meth., 4 ed., 3, 745 (1900); compare Watts’ Dict. of Chem., 


1, 271 (1894). G. Schultz, Chemie des Steinkohlenteers, 1, 289 (1886); 
compare Thorpe’s Dict. of Appld. Chem., 2 ed., 1, 162 (1895). 


ANTIMONY OXIDE 


(AntIMoNoUs OxipE; ANTIMONY TRIOXIDE) 
Sb.O3. Mol. Wt. 288.4. 


A white powder, insoluble in water, but soluble in hydro- 
chlorie acid, tartaric acid, alkali bitartrates, and in solutions 
of potassium or ‘sodium hydroxide. Antimony trioxide is 
neutral to litmus paper. 


TESTS OF PURITY 


Arsenic. — On dissolving 1 gm. of antimony trioxide in 
3 ec. of hydrochloric acid (sp. gr. 1.19), and adding 8 cc. of 
stannous chloride solution,. the mixture should not darken 
within one hour. 

Heavy Metals. — Dissolve 1 gm. of antimony trioxide with 
the aid of heat in 30 cc. of sodium hydroxide solution (sp. 
er. 1.3). Dilute the solution with 20 cc. of water and add 
hydrogen sulphide water. Neither a white nor a brownish- 
black precipitate should develop. 

Chlorides. — Dissolve 1 gm. of antimony trioxide with the 


CHEMICAL REAGENTS 65 


aid of heat in 30 ec. of sodium hydroxide solution (sp. gr. 1.3). 
Add to the solution 70 cc. of nitric acid, filter, and to the 
filtrate add silver nitrate solution. The liquid may exhibit 
at most a slight turbidity, but no precipitate should form. 


ARSENIC TRIOXIDE 


(ArsENous Acip; (Acip) ARSENOUS ANHYDRIDE) 
As:Os. Mol. Wt. 198. | 
White, vitreous, or porcelain-like pieces, or white powder, 
soluble in 15 parts of boiling water. 


TESTS OF PURITY 


Non-volatile Matter. — 1 gm. of arsenic trioxide cautiously 
heated in a porcelain dish should completely volatilize and 
leave no weighable residue. (Use a hood!) 

Barium Sulphate, Talcum, Calcium Sulphate, etc. — 0.5 gm. 
of arsenic trioxide should be perfectly soluble in a mixture 
of 5 cc. of ammonia water and 5 ec. of water, and should 
yield a clear solution. 

Arsenic Sulphide. — Dissolve 5 gm. of arsenic trioxide in a 
mixture of 5 cc. of sodium hydroxide solution and 15 ce. of 
water; on adding to the clear solution 2 drops of lead acetate 
solution, no color reaction should occur. 

Quantitative Determination. — Dissolve * 1 gm. of arsenic 
trioxide with the aid of 6 gm. of potassium bicarbonate in 
50 cc. of boiling water, then allow to cool to 15° C., and add 
sufficient water to make the whole measure 100 cc. Dilute 
10 cc. of this solution with 50 ce. of water, and titrate with 
decinormal iodine solution. 


* It may be quicker to dissolve 1 gm. in a freshly prepared solution of 
sodium hydroxide (sulphur-free), slightly acidulate with hydrochloric 
acid, and then add the 6 gm. of bicarbonate. No heat is necessary in 
this case. 


66 CHEMICAL REAGENTS 


1 cc. of decinormal I = 0.00495 gm. of As,O,, log. 69461. 


Norr. — Both the lump and the powder forms of arsenic trioxide must 
answer the above requirements. The tests here given should be carried 
out with the powdered preparation, as the whole pieces or lumps dissolve 
with difficulty. 

Regarding the use of arsenic trioxide in volumetric analysis, see Mohr’s 
Lehrb. Chem.-anal. Titriermeth., 7 ed., p. 389 ff. (1896); Sutton, Volumet. 
Anal., 9 ed., p. 139 (1904). 


AZOLITMIN 


Azolitmin is a particularly pure, water-soluble coloring 
matter made from litmus. It occurs in the form of blackish- 
violet scales. 

Azolitmin is used as an indicator, usually in 1 per cent 
solution. To make this, dissolve 1 gm. of azolitmin in 80 ce. 
of water with the aid of heat, then add 20 cc. of 85 per cent 
alcohol, and filter the solution when cold. 


TEST OF SENSITIVENESS 


Add 0.1 ce. of the above azolitmin solution to 50 ce. of 
distilled water, as free as possible from alkali and carbon 
dioxide. The bluish-red color of the liquid should be changed 
to red by the addition of, at most, 0.05 ec. of decinormal 
hydrochloric acid, and must be changed to bluish-violet by 
the addition of, at most, 0.05 cc. of decinormal potassium 
hydroxide. 

Notre. — The distilled water used in this test must be freed from 


carbon dioxide by boiling in a platinum vessel, and must be cooled in 
completely filled flasks with the exclusion of air. 


BARIUM ACETATE 
Ba(C2H;02)2 + H.O. Mol. Wt. 273.46. 


A white, crystalline powder, soluble in 2 parts of water 
and in about 100 parts of alcohol. 


CHEMICAL REAGENTS 67 


TESTS OF PURITY 


Chlorides. — The solution of 1 gm. of barium acetate in 
20 cc. of water, acidulated with nitric acid, must exhibit no 
turbidity on the addition of silver nitrate solution. 

Calcium and Alkalies. — Dissolve. 5 gm. of barium acetate 
in 200 ce. of water, add to the solution 2 cc. of hydrochloric 
acid and heat to boiling. Now add 15 cc. of 16 per cent 
sulphuric acid, allow to stand twelve hours, filter, and mix 
the filtrate with 85 per cent alcohol. At most a faint opales- 
cence should be observed; and on evaporating in a platinum 
dish and igniting, not more than 0.004 gm. of residue should 
remain. 

Heavy Metals. — 20 cc. of the 1: 20 aqueous solution should 
not acquire a dark color or afford a precipitate on the addi- 
tion of hydrogen sulphide water; ammonia water with ammo- 
nium sulphide solution should produce the same negative 
results. 

Nitrates. — The blue color imparted by 1 drop of 1: 1000 
indigo solution to a solution of 1 gm. of barium acetate in 
10 ce. of water should not disappear on the addition of 10 ce. 
of concentrated sulphuric acid. 


BARIUM CARBONATE 
BaCO3. Mol. Wt. 197.4. 
A white powder, almost insoluble in water. 


TESTS OF PURITY 


Solubility in Dilute Hydrochloric Acid. —5 gm. of barium 
carbonate should be completely soluble in 10 ec. of hydro- 
chloric acid diluted with 50 cc. of water. 

Calcium and Alkalies. — Dissolve 5 gm. of barium carbo- 
nate in 10 cc. of hydrochloric acid and 200 cc. of water,- and 
heat the solution to boiling. Then add 15 cc. of 16 per cent 


68 CHEMICAL REAGENTS 


sulphuric acid, allow to stand twelve hours, filter, and mix 
the filtrate with 85 per cent alcohol. Not more than a faint 
opalescence should be visible, and on evaporating in a plati- 
num dish and igniting, not more than 0.003 gm. of residue 
should remain. . 

Heavy Metals. — Neither hydrogen sulphide water, nor 
ammonia water with ammonium sulphide solution, should 
produce a dark color or a precipitate on being added to a 
solution of 1 gm. of barium carbonate in 5 cc. of hydrochloric 
acid and 15 cc. of water. 

Chlorides. — The solution of 1 gm. of barium carbonate 
in 5 ee. of nitric acid and 15 ce. of water (solution is hastened 
by heating) should not be affected by silver nitrate solution. 

Nitrates. — The blue color imparted by 1 drop of a 1: 1000 
indigo solution to the solution of 1 gm. of barium carbonate 
in 10 ce. of diluted acetic acid should not disappear on the 
addition of 10 cc. of concentrated sulphuric acid. 


Notre. — Regarding the volumetric determination of barium carbonate, 
see Mohr’s Lehrb. Chem.-anal. Titriermeth., 7 ed., p. 133 (1896); Sutton, 
Volumet. Anal., 9 ed., p. 70 (1904). 


BARIUM CHLORIDE 
BaCl. + 2H:O. Mol. Wt. 244.33. 
Colorless crystals, soluble in 2.5 parts of cold, and in 1.5 


parts of hot, water, and insoluble in absolute alcohol. The 
aqueous solution is neutral to litmus paper. 


TESTS OF PURITY 


Alkalies. — Dissolve 3 gm. of barium chloride in 100 ce. 
of water, add 2 cc. of hydrochloric acid and heat to boiling; 
then add 10 ec. of 16 per cent sulphuric acid, allow to stand 
twelve hours, and filter. On evaporating the filtrate in a 
platinum dish and igniting, a residue weighing more than 
0.001 gm. should not remain. 


CHEMICAL REAGENTS | OF 


Strontium and Calcium Chlorides. — On shaking 1 gm. of 
powdered barium chloride with 20 ce. of absolute alcohol 
five minutes, and then filtering, the filtrate on being evapo- 
rated and ignited should leave no weighable residue. 

Heavy Metals. — 20 cc. of the 1: 20 aqueous solution should 
not afford a dark coloration nor a precipitate when hydrogen 
sulphide water is added; nor when ammonia water and 
ammonium sulphide solution are added. 

Nitrates. — On adding 1 drop of a 1: 1000 indigo solution 
to ar solution of 1 gm. of barium chloride in 10 ce. of water, 
the blue color must not disappear on the addition of 10 cc. 
of concentrated sulphuric acid. , 

Chlorates. — On warming 2 gm. of powdered barium chlo- 
ride with 10 cc. of concentrated hydrochloric acid in a test 
tube, neither the crystals nor the liquid should acquire a 
yellow color; nor should the odor of chlorine become per- 
ceptible. 

BARIUM DIOXIDE 


(BaRIUM SUPER- OR PEROXIDE) 
BaOz. Mol. Wt. 169.4. 


White, or grayish-white powder, insoluble in water, but 
soluble in cold hydrochloric acid with the formation of 
hydrogen peroxide. The preparation should contain at least 


82 per cent of BaO,. 
« 


TEST OF PURITY 


Quantitative Determination. — Introduce 1 gm. of barium 
peroxide into a graduated flask of 100 cc. capacity, and add 
to it 5 gm. of potassium iodide; dissolve in 30 cc. of water 
and 10 cc. of hydrochloric acid, and allow the mixture to 
stand in the stoppered flask for about half an hour, with 
frequent shaking. Then fill the flask to the mark, mix, and 
titrate 10 cc. of the mixture with decinormal sodium thio- 


10. CHEMICAL REAGENTS 


sulphate solution, using starch solution as the indicator. At 
least 9.7 cc. of decinormal sodium thiosulphate should be 
required. 

1 cc. of decinormal Na,S8,0, = 0.00847 gm. of BaO,, log 
92788. 


BARIUM HYDROXIDE 


(Barium HypRATE) 
Ba(OH), + 8H,0. Mol. Wt. 315.54. 

White crystals, soluble in 20 parts of cold, and in 3 parts 
of boiling, water, a trace of barium carbonate almost inva- 
riably remaining undissolved. The aqueous solution is alka- 
line to litmus paper. 


TESTS OF PURITY 


Chlorides. — The solution of 1 gm. of barium hydroxide 
in 5 ce. of nitric acid and 15 ec. of water should not be 
affected by silver nitrate solution. 

Calcium and Alkalies. — Dissolve 3 gm. of barium hydrox- 
ide in 100 ce. of water, add 5 cc. of hydrochloric acid, and 
heat to boiling. Then add 10 ce. of diluted sulphuric acid, 
allow to stand twelve hours, and filter. On evaporating the 
filtrate in a platinum dish and igniting, a residue weighing 
more than 0.002 gm. should not remain. 

Heavy Metals. — 20 cc.. of the 1:20 aqueous solution 
acidulated with hydrochloric acid should not acquire a dark 
color, nor yield a precipitate on the addition of hydrogen 
sulphide water; nor should it do so on adding ammonia water 
to alkaline reaction, followed by ammonium sulphide solution. 

Sulphides. — The 1:20 aqueous solution of barium hy- 
droxide, when acidulated with hydrochloric acid, should not 
have an odor of hydrogen sulphide, nor should it acquire a 
dark color on adding lead acetate solution. 

Quantitative Determination. — Dissolve 1 gm. of barium 


CHEMICAL REAGENTS 71 


hydroxide in 100 cc. of water, add 1 drop of methyl orange 
solution, and titrate with normal hydrochloric acid. Not 
less than 6.3 cc. of the normal acid should be necessary to 
produce the red end-point. 
1 cc. of normal HCl = 0.15777 gm. of Ba(OH), + 8H,0, 
log. 19802. 
BARIUM HYDROXIDE SOLUTION 


(BARYTA WATER) 


A clear, colorless liquid, of strongly alkaline reaction. 
Baryta water contains 3.3 per cent of crystallized barium 
hydroxide, Ba(OH), + 8H,0. 


TESTS OF PURITY 


The tests to be made are those given under Barium Hy- 
droxide. But for each gram of crystallized barium hydrox- 
ide, 30 cc. of baryta water are to be taken. The quantita- 
tive determination is made as follows. 

Quantitative Determination. — Titrate 50 cc. of baryta 
water with normal hydrochloric acid, using methyl orange 
as the indicator. At least 10.5 ec. of normal hydrochloric 
acid should be required to produce the red end-point. 

1 ce. of normal HCl = 0.15777 gm. of Ba (OH), + 8H,0, 
log. 19802. | 

BARIUM NITRATE 
Ba(NOsz)2, Mol. Wt. 261.48. 


Colorless crystals, soluble in 20 parts of cold, and in 2.8 
parts of boiling, water. The aqueous solution is neutral to 
litmus paper. Barium nitrate is insoluble in absolute alcohol. 


TESTS OF PURITY 
Chlorides. — The 1:20 aqueous solution acidulated with 
nitric acid should show no change on the addition of silver 
nitrate solution. 


72 CHEMICAL REAGENTS 


Alkalies and Heavy Metals. — The test is to be carried out 
as described under Barium Chloride. 


BARIUM SULPHIDE 


Gray, hard, amorphous pieces, prepared by fusing a mixture 
of heavy-spar, powdered coke, and sodium chloride. 

On allowing hydrochloric acid to flow over barium sulphide, 
a uniform current of hydrogen sulphide should be generated. 


TEST OF PURITY 


Arsenic. — Heat 100 cc. of nitric acid (sp. gr. 1.3) in a 
porcelain dish to 70 to 80° C., and add 10 gm. of finely pow- 
dered barium sulphide, gradually, in quantities of 0.2 to 0.3 
gm. at a time; when all has been added, heat to boiling. 
Then add to the mixture 100 cc. of arsenic-free, dilute sul- 
phuric acid (1:5), evaporate on the water-bath as far as 
possible; continue to heat on the sand-bath until vapors of 
sulphuric acid begin to be evolved; cool, and finally stir the 
cooled residue with 100 cc. of water. . ea 

Set a Marsh apparatus in operation, using 20 gm. of arsenic- 
free, granulated zine and dilute (1:5) sulphuric acid, and 
then introduce the above residue suspended in water, in 
small quantities at a time, into the generating flask of the 
Marsh apparatus. No deposit of arsenic should be observable 
in the reduction tube after the apparatus has been in opera- 
tion two hours. 

Notr.— This chemical serves for the preparation of arsenic-free 


hydrogen sulphide. The hydrochloric acid to be used for this purpose 
is to be tested for arsenic. 


BENZENE 
(BENZOL) 
CeHo. Mol. Wt. 78.04. 
A clear, colorless liquid, of characteristic odor, insoluble 
in water, but easily soluble in alcohol and in ether. Benzene 


CHEMICAL REAGENTS 73 


solidifies at 0° C. to rhombic, crystalline scales, which melt 
at + 4° C. Its specific gravity is 0.883, and it boils at 
80.5° C. : 


TESTS OF PURITY 


Thiophene.* — On shaking 50 cc. of benzene with 20 cc. of 
concentrated sulphuric acid, the sulphuric acid should remain 
colorless; on now adding a crystal of isatin, and again shaking 
and allowing to stand one hour, the sulphuric acid should 
have neither a green nor a blue color. 

Carbon Disulphide.t — Thoroughly mix 50 cc. of benzene 
with 50 gm. of alcoholic potassium hydroxide solution (11 gm. 
of potassium hydroxide in 90 gm. of absolute alcohol), and 
allow the mixture to stand several hours at a temperature 
of about 20° C. Shake with about 100 cc. of water, remove 
the aqueous solution from the benzene, neutralize the latter 
with acetic acid, and add copper-sulphate solution. No 
precipitate should form. 


BENZIDINE 


(PARADIAMINODIPHENYL) 
(CoH1)2-(NHe2)2. Mol. Wt. 184.17. 
A grayish-yellow, crystalline powder, melting at 122° C. 
Benzidine is very difficultly soluble in cold water, but more 
readily in boiling water, in alcohol, and in ether. 


TEST OF PURITY 


Sulphur and Sulphates. — Thoroughly mix 5 gm. of ben- 
zidine with a mixture of 5 gm. of anhydrous sodium carbonate 


* See C. Schwalbe: “On the Sulphur Content of Pure Benzenes ”; 
Ztschr. Farb.-Textl. Ind., 3, 461 (1904); J. Chem. Soc. 88, I, 124 (1905). 
Ztschr. Farb.-Textl. Ind., 4, 113 (1905); J. Soc. Chem. Ind., 24, 271 (1905). 

+ F. Frank: Chem. Ind., 24, 237, 262 (1901) [or Chem. Centralb., (5) 
5, I, 1251 (1901)]; J. Soc. Chem. Ind., 20, 566 (1901). 


74 CHEMICAL REAGENTS 


and 2 gm. of potassium nitrate, and cautiously incinerate in 
a platinum crucible. When cold, dissolve the melt in 50 ce. 
of water, filter, add to the filtrate 20 cc. of hydrochloric acid, 
and heat to boiling. On now adding barium chloride solu- 
tion, no precipitate of barium sulphate should form on 
standing twelve hours. 


BENZIN 
(PETROLEUM ETHER; PETROLEUM BENzIN) 


A colorless, non-fluorescent, very inflammable liquid of 
strong but not unpleasant odor. Specific gravity 0.640 to 
0.670. Benzin distils between 40 and 75° C., and does not 
solidify at 0° C.* 

, TESTS OF PURITY 

Non-volatile Matter and Heavy Oils. — 20 gm. of benzin 
warmed on the water-bath should volatilize and leave no 
residue. When dropped upon paper, and allowed to evapo- 
rate, it should leave no greasy spot. 

Sulphur Compounds or Reducing Agents. — Mix 1 cc. of 
benzin with 5 ce. of a solution of silver nitrate in alcoholic 
ammonia; on plunging the test-tube containing the mixture 
into water of about 50° C., no brown coloration should develop. 


BISMUTH SUBNITRATE 
(BismutH Basic NITRATE) 


A white, microcrystalline powder, insoluble in water and 
in alcohol, but soluble in diluted hydrochloric, nitric, or 
sulphuric acid. On shaking bismuth subnitraté with water, 
it imparts an acid reaction to the latter. 3 


* Benzin is a mixture of various hydrocarbons. It has, therefore, 
no sharp boiling point, but distils within rather wide limits. The test- 
ing of benzin for benzene by nitrating the latter with nitro-sulphuric 
acid was not adopted here, because it is impossible to obtain a benzin 
that will stand this test. 


CHEMICAL REAGENTS 75 


TESTS OF PURITY 


Carbonates, Lead, Copper, Salts of the Alkalies, etc. — 
0.5 gm. of bismuth subnitrate should completely dissolve in 
25 ec. of cold 16 per cent sulphuric acid without the evolu- 
tion of carbon dioxide, and should yield a clear solution. 
10 cc. of this solution, with an excess of ammonia water, 
should yield a colorless filtrate. Another 10 cc. of this 
solution, diluted with 100 cc. of water and treated with 
hydrogen sulphide to completely precipitate the bismuth, 
should yield a filtrate leaving no weighable residue on evapo- 
ration and ignition. 

Chlorides. — On adding silver nitrate solution to a solution 
of 0.5 gm. of bismuth subnitrate in 5 ce. of nitric acid, not 
more than a slight opalescent turbidity should develop. 

Sulphates. — The solution of 0.5 gm. of bismuth sub- 
nitrate in 5 cc. of nitric acid should show no change on the 
addition of 5 to 10 drops of barium nitrate solution. 

Ammonia.— On warming 1 gm. of bismuth subnitrate 
with 10 ce. of sodium hydroxide solution (sp. gr. 1.3), no 
ammonia should be evolved (to be ascertained by moistened 
litmus paper). 

Residue on Ignition. — On igniting 1 gm. of bismuth sub- 
nitrate, there should remain a residue of bismuth oxide 
weighing 0.79 to 0.82 gm. ; 

Arsenic. — The residue of bismuth oxide obtained above 
is triturated to a fine powder, and dissolved in sulphuric acid 
with heat. Set a Marsh apparatus in operation, using 20 gm. 
of arsenic-free, granulated zinc, and dilute (1:5) sulphuric 
acid, then introduce the bismuth solution in small quantities 
at a time into the evolution flask. No deposit of arsenic 
should be visible in the reduction tube within half an 
hour. 


76 CHEMICAL REAGENTS 


BROMINE 
Br. Atomic Wt. 79.96. 


A dark red, almost black liquid, of specific gravity 2.97 to 
2.99, and boiling at 63° C. Bromine dissolves in about 
30 parts of water. It is easily soluble in alcohol, ether, 
chloroform, and carbon disulphide. 


TESTS OF PURITY 


Non-volatile Matter.— 5 gm. of bromine warmed in a porce- 
lain dish on the water-bath should volatilize and leave no 
weighable residue. 

Sulphuric Acid, Chlorine, and Organic Bromine Compounds 
(Bromoform; Carbon Tetrabromide). — 5 gm. of bromine dis- 
solve without turbidity of any kind in 100 cc. of water 
after adding, by drops, 20 cc. of ammonia water.* Evapo- 
rate to dryness the solution of ammonium bromide thus 
obtained, and test for: 

(a) Sulphuric Acid. 

Dissolve 2 gm. of the ammonium bromide in 60 cc. of 
water, and add 0.5 ec. of hydrochloric acid followed 
by barium chloride solution. A precipitate of barium 
sulphate should not form on standing twelve 
hours. 

(b) Chlorine. 

Dissolve 0.1 gm. of the ammonium bromide in 10 ce. 
of water, and mix with 4 cc. of ammonium carbonate 
solution (1 part of ammonium carbonate, 1 part of 
ammonia water, and 3 parts of water), then add 

-12 ec. of decinormal silver nitrate solution, filter, 


* Organic bromine compounds gradually separate out in the form of 
oily drops. 


CHEMICAL REAGENTS V7 


and acidulate the filtrate with nitric acid. Only a 
slight opalescence should develop.* 

Iodine. — Dissolve 1 gm. of bromine in 40 cc. of water, 
add 4 gm. of powdered iron, and shake two to three minutes. 
Filter, add starch solution to the filtrate, and cautiously 
allow a few drops of bromine water to flow upon the surface. 
A blue zone should not form at once below the yellowish 
upper portion of the liquid. 


BROMINE WATER 


A saturated, aqueous solution, containing about 3 per cent 

of Br. 
TESTS OF PURITY 

Sulphuric Acid. — Add 0.5 ec. of hydrochloric acid and 
_ barium chloride solution to 50 cc. of bromine water, and boil 
the liquid until the bromine has been completely expelled 
from it. No precipitate of barium sulphate should separate 
on standing one hour. . 

Bromine Content. — Let 10 cc. of bromine water run into 
a solution of 5 gm. of potassium iodide in 100 cc. of water, 
allow to stand half an hour in a stoppered flask, and then 
titrate with decinormal sodium thiosulphate solution. 

1 cc. of decinormal Na,S,O, = 0.007996 gm. of Br., log. 
90287. 

BRUCINE 
CosHog6N2O, + 2H207. Mol. Wt. 430.32. 


Small, white crystals, difficultly soluble in cold, but more 
readily soluble in boiling, water. Brucine is easily soluble 


* Some opalescence always occurs because silver bromide is not abso- 
lutely insoluble in ammonium carbonate solution. 

Regarding the quantitative determination of chlorine in bromine, see 
Topf. Pharm. Ztg., 37, 364 (1892). 


t Brucine also crystallizes with 4 molecules of water; then it dissolves 
in 320 parts of cold, and in 150 parts of boiling, water. 


78 CHEMICAL REAGENTS 


in 85 per cent alcohol, and in chloroform. The aqueous 
solution of brucine is alkaline to litmus paper, and is levo- 
gyrate. When dried at 100° C., brucine melts at 178° C. 


TESTS OF PURITY 


Water of Crystallization.—1 gm. of brucine dried at 
100° C. to constant weight should lose not more than 0.083 gm. 

Nitric Acid. — 0.01 gm. of brucine should dissolve in 5 ce. 
of pure concentrated sulphuric acid, and yield a colorless or, 
at most, scarcely perceptible faint pink color.* 

Strychnine. — Treat 0.5 gm. of brucine with 5 gm. of 
absolute alcohol at the ordinary temperature for one hour, 
with frequent shaking. Filter, transfer a portion of the 
undissolved substance to a watch glass, allow it to dry there- 
on, and then dissolve it in a few drops of concentrated sul- 
phuric acid. To this solution add a small crystal of potassium - 
dichromate. A play of colors, from blue through violet and 
red into green, is evidence of the presence of strychnine. 

Quantitative Determination. — Dissolve 0.25 gm. of brucine 
in 50 ec. of 85 per cent alcohol, and titrate with decinormal 
hydrochloric acid, using lacmoid as the indicator. At least 
5.8 cc. of decinormal acid should be required to produce the 
red end-point. 

1 ce. of decinormal HCl = 0.043032 gm. of C,,H,,.N,O, + 
2H,0, log. 63379. 


CADMIUM BOROTUNGSTATE SOLUTION 


A perfectly clear, yellowish, or light brown, liquid, me 
a specific gravity of 3.28. 


CADMIUM AND POTASSIUM IODIDE 
(PorasstumM—CapMiIuM JopDIDE) 
A white powder, easily soluble in water and in alcohol. 


* The sulphuric acid should be tested with diphenylamine to insure 
the absence of nitric acid. 


CHEMICAL REAGENTS 79 


Cadmium and potassium iodide readily acquires a slight 
yellowish color on keeping. 


TESTS OF PURITY 


Foreign Metals. — 

(a) Dissolve 1 gm. of cadmium and potassium iodide in 
20 ec. of water, add to the solution 2 ec. of potassium 
hydroxide solution, and filter. Neither before nor 
after acidulating with hydrochloric acid should the 
filtrate yield a precipitate with hydrogen sulphide 

~ water. 

(b) Dissolve 1 gm. of cadmium and noudehinn lodide in 
30 cc. of water, and add to the solution 5 cc. of 
ammonia water. The liquid should remain clear 
and colorless on shaking. 

Sulphates. — The 1:20 aqueous solution acidulated with 
hydrochloric acid should not be affected by barium chloride 
solution. 

Iodic Acid. — The 1:20 solution freshly prepared with 
‘ boiled water should not immediately give a blue color on 
adding starch solution followed a 2 or 3 drops of dilute 
sulphuric acid. 


CALCIUM CARBONATE PRECIPITATED 
CaCO;3. Mol. Wt. 100.1. 


A white, crystalline powder, almost insoluble in pure water 
(1: 27000), but somewhat soluble in carbonated water. 


TESTS OF PURITY 


Solubility in Hydrochloric, Nitric, and Acetic Acids. — 5 gm. 
of calcium carbonate should be completely dissolved by 25 cc. 
of hydrochloric acid, and by 25 ec. of nitric acid, and by 
60 cc. of 30 per cent acetic acid. The solutions must be 
clear and colorless. 


80 — CHEMICAL REAGENTS 


Heavy Metals. — Dissolve 1 gm. of calcium carbonate in 
5 ec. of hydrochloric acid and 25 cc. of water. This solu- 
tion should not afford a precipitate or a green color with 
hydrogen sulphide water; nor with ammonia water in excess 
accompanied by 2 to 3 drops of ammonium sulphide solution. 

Magnesium. — Dissolve 1 gm. of calcium carbonate in 
5 ec. of hydrechloric acid and 5 ce. of water. To this solu- 
tion add 10 cc. of ammonia water and an excess of ammonium 
oxalate solution, allow to stand five hours, filter, and add 
to the filtrate sodium phosphate solution. No precipitate 
should form on standing twelve hours. | 

Sulphates. — Dissolve 1 gm. of calcium carbonate in 5 ce. 
of hydrochloric acid and 25 cc. of water, boil the solution 
five minutes, and add barium chloride solution. No precipi- 
tate of barium sulphate should form on standing twelve 
hours. 

Chlorides. — 1 gm. of calcium carbonate dissolved in 5 ce. 
of nitric acid and 25 cc. of water, must show no change on 
the addition of silver nitrate solution. 

Phosphates. — Dissolve 10 gm. of calcium carbonate in 
50 ec. of nitric acid, add 25 ce. of ammonium molybdate 
solution, and allow to stand twelve hours at a temperature 
of 30 to 40° C. No yellow precipitate should form. 

Alkalies and Calcium Oxide. — 1 gm. of calcium carbonate — 
shaken with 50 parts of boiled and cooled water should 
yield a filtrate without an alkaline reaction, which on evapo- 
ration and ignition should leave a residue weighing at most 
0.001 gm. 


CALCIUM CHLORIDE, CRYSTALS 
CaCl, + 6H,O. Mol. Wt. 219.09. 
Colorless crystals, deliquescent in the air, and easily soluble 
in water and in alcohol. The 1:10 solution should be neutral. 
to litmus paper. | 


CHEMICAL REAGENTS $1 


TESTS OF PURITY 


Substances Insoluble in Absolute Alcohol. — 2 gm. of cal- 
cium chloride should completely dissolve in 20 cc. of ab- 
solute alcohol. 

Heavy Metals. — 20 cc. of the 1: 10 aqueous solution should 
show no change on adding 1 cc. of hydrochloric acid and 
hydrogen sulphide water. On further adding 5 cc. of am- 
monia water and 2 to 3 drops of ammonium sulphide solu- 
tion, no green color should develop, nor should a precipitate 
form. 

Sulphates. — On adding barium chloride solution to the 
solution of 2 gm. of calcium chloride in 20 cc. of water acid- 
ulated with 0.5 ec. of hydrochloric acid, no precipitate should 
form on standing twelve hours. 

Ammonium Salts. — On boiling 2 gm. of calcium chloride 
with 10 ec. of sodium hydroxide solution, no ammonia should 
be evolved (to be ascertained by moistened litmus paper). 

Barium. — On adding 20 cc. of calcium sulphate solution 
to the solution of 2 gm. of calcium chloride in 20 cc. of water, 
no precipitate should form within three hours. 

Arsenic. — Introduce 10 gm. of arsenic-free, metallic zinc 
into the generating flask of a Marsh apparatus, and start the 
hydrogen with dilute (1:5) sulphuric acid. Dissolve 5 gm. 
of calcium chloride in 20 cc. of water, introduce the solution 
in “small quantities at a time into the Marsh apparatus, and 
maintain the stream of gas for about one hour. No deposit 
of arsenic should be visible in the reduction tube within 
this time. 


CALCIUM CHLORIDE, DRY, GRANULATED 


White, granular, porous masses in pieces the size of peas, 
the form preferred for drying gases. This is the preparation 
to be used for filling absorption tubes for the determination 


82 CHEMICAL REAGENTS 


of carbon dioxide, as in elementary analyses, but it should 
be previously rendered neutral by means of carbonic acid. 


CALCIUM CHLORIDE FUSED 


White crystalline masses; formula: practically CaCl,. Fused 
calcium chloride is chiefly used for drying liquids, e. 9: ethers, 
_ esters, ethereal oils, hydrocarbons, etc. 


CALCIUM HYDROXIDE 


(SLAKED LIME) 
Ca(OH). Mol. Wt. 74.11. 
A white, dry powder. 
The article is tested as to purity by the methods detailed 
under Calcium Oxide from Marble, on page 83. 


CALCIUM OXIDE, FROM ICELAND SPAR 
CaO. Mol. Wt. 56.1. 
White pieces in the form of Iceland spar crystals. 


TESTS OF PURITY 


Solubility and Sulphates. — 3 gm. of calcium oxide slaked 
with 10 cc. of water should completely dissolve in 15 cc. of 
hydrochloric acid without effervescence. Dilute the solution 
with 50 cc. of water, heat to boiling, and add barium chloride 
solution. On standing twelve hours, not more than a scarcely 

‘perceptible, unweighable trace of barium sulphate should be 
present. 

Phosphates. — Slake 3 gm. of calcium oxide with 10 ce. 
of water, dissolve in 25 cc. of nitric acid, and add 25 cc. of 
ammonium molybdate solution. No yellow precipitate should 
form on standing twelve hours at 30 to 40° C. 

Chlorides. — Slake 3 gm. of calcium oxide with 10 cc. of 


CHEMICAL REAGENTS 83 


water, dissolve in 20 cc. of nitric acid, and dilute the solution | 
with 10 cc. of water. The solution should show no change 
on the addition of silver nitrate solution. 

Iron. — Slake 1 gm. of calcium oxide with 5 cc. of water, 
and dissolve in 10 ec. of hydrochloric acid. The solution 
should not immediately afford a blue color on adding 0.5-ce. 
of potassium ferrocyanide solution. 


CALCIUM OXIDE, FROM MARBLE 


(LIME) 
CaO. Mol. Wt. 56.1. 

White pieces of granular structure which develop much 
heat on being sprinkled with water, and which become con- 
verted into a fine, dust-like powder, or a pasty mass, according 
to the quantity of water used. Calcium oxide is soluble in 
about 800 parts of cold, and in 1300 parts of boiling, water. 


TESTS OF PURITY 


Carbonates, Silica, Alumina, and Sulphates. — Slake 5 gm. 
of calcium oxide with 10 ec. of water. The magma so ob- 
tained should almost completely dissolve in 30 cc. of hydro- 
chloric acid without strong effervescence. Dilute the solution 
with 20 cc. of water, and filter. (The insoluble residue, after 
ignition, should weigh at most 0.005 gm.) To 25 ce. of the 
filtrate, add barium chloride solution; the liquid should show 
no change within ten minutes. Supersaturate 25 cc. of the 
filtrate with ammonia water; the liquid should not be ren- 
dered more than slightly opalescent. 

Chlorides. — Slake 1 gm. of calcium oxide with 3 cc. of 
water, dissolve in 10 cc. of nitric acid, dilute the solution 
with 10 ec. of water, filter, and add silver nitrate solution to 
the filtrate. The liquid should not be rendered more than . 
slightly opalescent. 


84 CHEMICAL REAGENTS 


CALCIUM PHOSPHATE, DIBASIC 


(SEconDARY CaLctuM PHospHaTE; Dicatctum PHOSPHATE) 
CaHPO, + 2H.O. Mol. Wt. 172.14. 


A white, crystalline powder, easily soluble in hydrochloric, 
nitric, or phosphoric acid, without effervescence; it is diffi- 
cultly soluble in water, and in cold acetic acid. 

Dicalecium phosphate does not dissolve in boiling water 
without decomposition; it produces a liquid of acid reaction 
and an amorphous residue, the composition of which approx- 
imates that of the neutral salt. 


TESTS OF PURITY 


Arsenic. — The test is carried out as described under 
Calcium Phosphate, Monobasic on page 85, using a solution 
of 2 gm. of dicalcium phosphate in 5 ec. of hydrochloric acid 
and 15 cc. of water 

Chlorides. — Dissolve 1 gm. of dicalcium phosphate in 
5 ec. of nitric acid and 15 cc. of water; on adding silver 
nitrate solution, not more than a slight opalescent turbidity 
should be visible. | | 

Heavy Metals. — The solution of 1 gm. of dicalcium phos- 
phate in 5 ec. of hydrochloric acid and 15 cc. of water should 
afford a pure white precipitate on the addition of hydrogen 
sulphide water and 10 cc. of ammonia water. 

Sulphates. — On shaking 1 gm. of dicalcium phosphate 
with 20 ec. of water and filtering, the filtrate, on adding 1 cc. 
of hydrochloric acid and barium chloride solution, should 
develop no precipitate within twelve hours. 

Residue on Ignition. — On ignition, dicaletum phosphate 
should yield 74 to 75 per cent of its weight of residue.* 


* On ignition, dicalcium phosphate is converted into calcium pyrophos- 
phate, whereby it theoretically loses 26.12 per cent of water. 


CHEMICAL REAGENTS 85 


CALCIUM PHOSPHATE, MONOBASIC 


(Catctum BreHosPpHATE; CALciuM AcIpD (oR SUPER) PHos- 
PHATE; PRIMARY CALCIUM PHOSPHATE; 
MoNOCALCIUM PHOSPHATE) 

Ca(H2PO,)2 + H:O. Mol. Wt. 252.14. 

Colorless, pearly scales, which readily deliquesce in the air. 

Calcium biphosphate dissolves in much water, apparently 
without decomposition; with a small quantity of water, an 
amorphous salt separates, richer in calcium, while the solution 
exhibits a strongly acid reaction. 

On heating a 1: 20 aqueous solution of calcium biphoapkate 
to boiling, a precipitate forms. 


TESTS OF PURITY 


Arsenic. — Introduce 10 gm. of arsenic-free, granulated zinc 
into the generating flask of a Marsh apparatus, and start the 
stream of hydrogen by adding dilute (1:5) sulphuric acid. 
After the apparatus and reagents have been tested in the 
usual manner, dissolve 2 gm. of calcium biphosphate in 5 cc. 
of hydrochloric acid and 15 cc. of water. Introduce this 
solution into the Marsh apparatus, and. maintain the flow 
of gas for about one hour. No deposit of arsenic should be 
visible in the reduction tube within this time. 7 

Chlorides. — A solution of 1 gm. of calcium biphosphate in 
5 cc. of nitric acid and 15 cc. of water should not be ren- 
dered more than slightly opalescent on the addition of silver 
nitrate solution. 

Heavy Metals. — On adding hydrogen sulphide water and 
10 cc. of ammonia water to a solution of 1 gm. of calcium 
biphosphate in 5 cc. of hydrochloric acid and 15 ce. of water, 
a pure white precipitate should form. 


Norr. — The presence of a small quantity of sulphuric acid in this 
preparation cannot be avoided. It is due to the customary methods of 
manufacturing the salt. 


86 CHEMICAL REAGENTS 


CALCIUM PHOSPHATE, TRIBASIC 


(Tertiary Catcitum PHospHats; TRICALCIUM PHOSPHATE) 
Cas(POu.)o. Mol. Wt. 310.3. 


A white, amorphous powder, insoluble in cold water. 
Tricaletum phosphate is gradually decomposed by boiling 
-water into an insoluble basic salt and an easily soluble acid 
salt. It is easily soluble in hydrochloric or nitric acid, and 
without effervescence. 


TESTS OF PURITY 


Arsenic. — The test is carried out as detailed under Cal- 
cium Phosphate, Monobasic, on page 85, using a solution of 
2 gm. of tricalcium phosphate in 5 cc. of hydrochloric acid 
and 15 cc. of water. 

Sulphates. — Shake 1 gm. of tricalcium phosphate with 
20 cc. of water, filter, and add to the filtrate 1 ec. of hydro- 
chloric acid and barium chloride solution. No precipitate 
should form on standing twelve hours. 

Chlorides. — The solution of 1 gm. of tricalcium phosphate 
in 5 ce. of nitric acid and 15 cc. of water should not show 
more than a slight opalescent turbidity on adding silver 
nitrate solution. 

Heavy Metals. — The solution of 1 gm. of tricalcium phos- 
phate in 5 ec. of hydrochloric acid and 15 ec. of water should 
yield a pure white precipitate on adding hydrogen sulphide 
water and 10 cc. of ammonia water. 


CALCIUM SULPHATE 


(GYPSUM) 
CaSO, + 2H,O. Mol. Wt. 172.19. 
A fine, white powder, difficultly soluble in water (about 
1: 500). 


CHEMICAL REAGENTS 87 


TESTS OF PURITY 

Iron, Magnesium, and Alkalies. —On warming 2 gm. of 
calcium sulphate with 10 ce. of hydrochloric acid and 100 cc. 
of water, a clear solution should result, which, on the addi- 
tion of 15 ec. of ammonia water and a few drops of ammo- 
nium sulphide solution, should not acquire a greenish or 
_ dark color. To the solution, no matter whether a precipitate 
of calcium sulphate has formed or not, add ammonium 
oxalate solution in slight excess, filter, evaporate the filtrate, 
and ignite in a platinum dish. There should not remain a 
residue weighing more than 0.001 gm. 


CALCIUM SULPHIDE 
(SULPHURATED LIME) 


Light-gray cubes, from which dilute hydrochloric acid sets 
free copious quantities of hydrogen sulphide gas. 


TEST OF PURITY 
Arsenic. — This is carried out as detailed under Barium 
Sulphide on page 72. 


Notre. — This preparation serves for the generation of arsenic-free 
hydrogen sulphide. The hydrochloric acid used for this purpose should 
also be tested for arsenic. 


CARBON DISULPHIDE 
CS2. Mol. Wt. 76.12. 


A clear, colorless, neutral liquid of specific gravity 1.270 
to 1.272, and boiling at 46 to 47° C. 


TESTS OF PURITY 
Non-volatile Matter.— On evaporating 50 cc. of carbon 
disulphide on the water-bath, no weighable residue should 
remain.* 


* Under the influence of light, carbon disulphide becomes yellowish, 
and then leaves a ‘sseane residue on evaporation. 


88 CHEMICAL REAGENTS 


Hydrogen Sulphide and Foreign Organic Sulphur Com- 

pounds. — 

(a) On shaking 10 ce. of carbon disulphide with lead 
carbonate, the latter should not acquire a brown 
color. 

(b) On shaking 2 ec. of carbon disulphide in a dry vessel 
with a globule of metallic mercury, the bright 
surface of the latter should not become covered 
with a dark, pulverulent coating. 

Sulphuric and Sulphurous Acids. — On shaking 10 ce. of 

carbon disulphide with 5 cc. of water, the latter should 
neither redden nor decolorize blue litmus paper. 


CARMINE 
(CARMINE I, [NAccARAT]) 


Bright red, light pieces, which are very friable and redu- 
cible to a fine powder. Carmine is insoluble in water, and in 
dilute acids, but is soluble in ammonia. 


TESTS OF PURITY 


Solubility. — 0.15 gm. should be almost completely soluble 
in a mixture of 5 ec. of ammonia water and 20 ce. of water, 
yielding a violet-red solution; only a small amount of floc- 
culent matter should remain undissolved. 

Ash. — 0.25 gm. of carmine cautiously incinerated in a 
porcelain crucible should not yield an ash weighing more 
than 0.02 gm. Particular attention should be paid to the 
odor of the decomposing carmine; it is similar to that yielded 
during the combustion of proteids. An odor. of bromine 
would point to a sophistication with an eosine-lake; and an 
odor of phenol would point to an admixture of pxeonine-lake. 


Notsr. — Regarding the adulterations of cochineal-carmine, see E. 
Donath, Dingl. pol. J., 294, 188 (1894); J. Soc. Chem. Ind., 14, 305 (1895). 


CHEMICAL REAGENTS 89 


Regarding the preparation of carmine solutions and carmine tinctures, 
see Merck’s Reagentien-Verzeichnis, p. 171 (1903); Cohn, Tests and Re- 


agents, p. 349 (1903). 

Regarding the composition of carmine and of carmine ash, see 8. Feitler, 
Ztschr. angew. Chem., 5, 136 (1892) [or Ztschr. anal. Chem., 32, 627 
(1893)]; J. Soc. Chem. Ind., 12, 256 (1893). 


CHARCOAL, ANIMAL 
(Broop CHarcoaL, PurirreD By AcID) 
A dry, light, black powder. 


TESTS OF PURITY 


Material Soluble in Water. — Exhaust 1 gm. of animal 
charcoal by boiling with 20 cc. of water, filter, and evaporate 
the filtrate to dryness. The residue should not weigh more 
than 0.003 gm. 

Material Soluble in Alcohol. — Heat a mixture of 1 gm. of 
animal charcoal and 20 cc. of alcohol to boiling, and filter. 
The filtrate should leave no weighable residue on evaporation. 

Sulphates, Chlorides, and Nitrates. — 

(a) Boil 1 gm. of animal charcoal with 50 cc. of water for 
a few minutes, and filter. The filtrate should be 
colorless and neutral. On adding to 10 ec. of the 
filtrate some barium nitrate solution, no immediate 

turbidity should be produced. 

(b) On adding silver nitrate solution to 10 cc. of the 
filtrate, not more than a slight opalescence should 
develop. 

(c) On adding 1 drop of 1: 1000 indigo solution and 5 ce. 
of concentrated sulphuric acid to 10 cc. of the fil- 
trate, the blue color of the solution should not dis- 
- appear. 

Copper, Iron, and Calcium. — Boil 1 gm. of animal charcoal 

with 40 cc. of water and 10 cc. of hydrochloric acid for about 


90 CHEMICAL REAGENTS 


five minutes, filter, and to 10 cc. of the filtrate add 25 ec. 
of ammonia water; the liquid should not acquire a blue color, 
nor should a flocculent precipitate form. On the further 
addition of a -few drops of ammonium sulphide and am- 
monium oxalate solutions, no turbidity should develop 
immediately. 3 

Residue on Ignition. — 1 gm. of animal charcoal should 
leave a residue weighing not more than 0.10 gm. on ignition. 

Hydrogen Sulphide. — Heat 1 gm. of animal charcoal with 
40 cc. of water and 10 cc. of hydrochloric acid, and test the 
escaping vapors with moistened lead acetate paper. The 
latter should not acquire a brown color. 

Decolorizing Power. — Dissolve 50 gm. of caramel (sugar 
coloring; burnt sugar) in 50 ec. of water, add 100 cc. of 
85 per cent alcohol, dilute the whole to 1 liter, allow to 
stand for several days, and then filter. Dilute 5 cc. of this 
caramel solution with 50 cc. of water, add 1 gm. of animal 
charcoal, boil the mixture ten minutes under a reflux con- 
denser, and then filter. The filtrate should be perfectly 
colorless. | 

CHLORINE WATER 


A clear, pale, greenish-yellow liquid, having a strong odor 
of chlorine. The liquid should contain about 0.4 per cent of Cl. 
TESTS OF PURITY 


Non-volatile Matter. — 20 gm. of chlorine water evaporated 

in a glass dish on a water-bath should leave no weighable 
residue. 
_ Chlorine Content. — Let 25 gm. of chlorine water run into 
a flask containing a solution of 1 gm. of potassium iodide in 
25 ec. of water. Add a few drops of starch solution, and 
titrate the liberated iodine with decinormal sodium thio- 
sulphate solution, of which at least 28.2 cc. should: be used to 
cause the blue color to disappear. 


CHEMICAL REAGENTS 91 


1 ec. of decinormal Na,S,O, = 0.003545 gm. of Cl, log. 
54962. 

Hydrochloric Acid.* — Shake 20 gm. of chlorine water 
with about 5 gm. of pure mercury vigorously for five minutes. 
Filter, add phenolphthalein to the solution, and run in 
normal potassium hydroxide solution, by drops, until a red 
color appears. Not more than 0.1 cc. of normal alkali should 
be required to produce the red end-point. 3 


CHLOROFORM > 
CHCl;. Mol. Wt. 119.35. 


A clear, colorless, very volatile liquid, slightly soluble in 
water (1:200), but miscible in all proportions with alcohol, 
ether, and fatty and volatile oils. - Chloroform ‘has a specific 
gravity of 1.485 to 1.489, and boils at 60 to 62° C.f 


TESTS. OF PURITY 


Free Acid. — Vigorously shake together 20 ce. of chloro- 
form and 10 ec. of water for half a minute; after the chloro- 
form has separated, draw off the aqueous layer with a pipette. 
The liquid should not redden blue litmus paper, nor should 
it acquire an opalescence when overlaid on a mixture of 
2.5 ec. of water and 2.5 ce. of silver nitrate solution. 

Free Chlorine. — On shaking 5 cc. of chloroform with 
5 ec. of zine iodide-starch solution, the latter should not 
acquire a blue color, nor should the chloroform become 
colored. 

Foreign Organic Bodies. — On repeatedly shaking 20 ce. 


* Chlorine water, unless recently prepared, always contains hydro- 
chloric acid. 

t+ The readiness of pure (absolute) chloroform to decompose may be 
prevented by the addition of a small amount (up to 1 per cent) of pure 
absolute alcohol. The specific gravity and boiling point are somewhat 
changed by this addition. The alcohol may be removed from the chlo- 
roform by shaking it twice with double its volume of pure sulphuric acid, 
neutralizing the acid with granulated potassium carbonate, and distilling. 


92 CHEMICAL REAGENTS 


of chloroform and 15 cc. of concentrated sulphuric acid in 
a glass-stoppered flask, 3 cm. wide, which has been rinsed 
previously with sulphuric acid, the acid should not acquire 
a color within one hour. 


CHROMIUM TRIOXIDE — FREE FROM SULPHURIC ACID 


( (Acrp) CHromic ANHYDRIDE) 
CrO;. Mol. Wt. 100.01. 


Dark, brownish-red needles, or rhombic prisms, very 
readily soluble in water. Chromium trioxide contains almost 
100 per cent of CrO,. 


TESTS OF PURITY 


Sulphuric Acid. — 2 gm. of chromium trioxide must afford 
a clear solution with 20 cc. of water. On adding to the 
solution 20 ec. of hydrochloric acid and 1 cc. of barium 
chloride solution, no turbidity should occur immediately. 

Potassium Sulphate and Potassium Chromate. — Ignite 0.2 
gm. of chromium trioxide in a porcelain crucible, triturate 
the residue with about 20 cc. of water, and filter. Evapo- 
rate the filtrate to dryness on a water-bath, dry the residue 
at 100° C., and weigh. The residue must not weigh more 
than 0.002 gm. 

Quantitative Determination. — Dissolve 5 gm. of chromium 
trioxide in water and dilute to 500 cc. Introduce 10 cc. of 
this solution into a stoppered flask of about 400 cc. capacity, 
dilute with 100 cc. of water, and add 5 gm. of potassium 
iodide and 2 cc. of hydrochloric acid. Allow the mixture to 
stand for about ten minutes with frequent shaking, then 
dilute with 200 cc. of water, and titrate with decinormal 
sodium thiosulphate solution. 

1 ec. of decinormal Na,S,0, = 0.003336 gm. of CrO,, log. 
52323. 


CHEMICAL REAGENTS 93 


COBALT NITRATE 


(CopaLrous NITRATE) 
Co(NOs)2 + 6H20. Mol. Wt. 291.17. 


Red, monoclinic prisms, deliquescent in moist air, and 
readily soluble in water and in alcohol. 


TESTS OF PURITY 


Sulphates. — A solution of 1 gm. of cobalt nitrate in 
20 ec. of water, to which have been added 0.5 cc. of hydro- 
chloric acid and a little barium chloride solution, should: not 
become turbid. 

Alkali Salts. — Precipitate the cobalt completely from a 
solution of 2 gm. of cobalt nitrate in 100 cc. of water by 
adding ammonia water and ammonium sulphide solution; 
filter, evaporate the filtrate to dryness, and ignite the residue. 
The weight of the latter should not exceed 0.005 gm. 

Zinc. — To a solution of 0.5 gm. of cobalt nitrate in 50 ce. 

of water, add 5 cc. of sodium hydroxide solution (sp. gr. 1.3); 
filter, and to the filtrate add ammonium sulphide solution. 
No precipitate should form. 
_ Lead and Copper. — Dissolve 2 gm. of cobalt nitrate in 
50 ce. of water, and add 2 ce. of nitric acid, followed by 
hydrogen sulphide water. The solution must show no 
change. 

Nickel.* — Dissolve 1 gm. of cobalt nitrate in 20 cc. of 
water, add 3 gm. of potassium cyanide, boil the solution 
until it has acquired a yellow color, filter, and to the filtrate 
add potassium hydroxide solution and bromine water. No 
brown color should develop. 7 


* Compare the method using nitrosobeta-naphthol. See Prescott and 
Johnson, Qualitative Chemical Analysis, p. 166 (1901). 


94 CHEMICAL REAGENTS 


COLLODION 


A colorless, or slightly yellowish, neutral, syrupy liquid, 
which, exposed in thin layers, evaporates, and leaves a 
tough, colorless film. Collodion contains about 4 per cent 


of soluble cotton. 
TESTS OF PURITY 


Acids. — Blue litmus paper, when immersed in collodion, 
should not be reddened immediately. 

Determination of Residue. — On evaporating 10 gm. of 
collodion on the water-bath, it should leave a residue, which, 
when dried at 100° C., should weigh 0.38 to 0.40 gm. 


COPPER, BY ELECTROLYSIS 
Cu. Atomic Wt. 63.6. 


i TESTS OF PURITY 

Foreign Metals. 

(a) Dissolve 10 gm. of copper in 60 ce. of nitric acid (sp. 
er. 1.3), and evaporate the solution to dryness on 
the water-bath. The residue should completely dis- 
solve in 50 ce. of water and 10 ce. of nitric acid 
(sp. gr. 1.3), yielding a clear solution (absence of 
antimony and tin). To the solution add 15 ce. of 
concentrated sulphuric acid (sp. gr. 1.84), evaporate 
on the water-bath as far as possible, heat the residue 
on a sand-bath until vapors of sulphuric acid begin 
to be evolved, and take up the residue with 100 cc. 
of water. No insoluble residue should remain 
(absence of lead). On adding 5 cc. of hydrochloric 
acid to the clear solution, no turbidity should ensue 
(absence of silver). Now add 150 ec. of ammonia 
water to the liquid, allow to stand three to four 
he«rs at 50 to 60° C., filter through an ashless filter, 


CHEMICAL REAGENTS 95 


wash with ammoniacal water until perfectly free 
from copper. Incinerate the filter with any pre- 
cipitate it may contain, and ignite. The residue 
should not weigh more than 0.001 gm. (iron and 
bismuth). | 

(b) Dissolve 10 gm. of copper in 60 ce. of nitric acid (sp. 

er. 1.3), add to the solution 15 cc. of concentrated 
sulphuric acid (sp. gr. 1.84), evaporate the solution 
on the water-bath as far as possible, and heat the — 
residue on a sand-bath until the vapors of sulphuric 
acid begin to be evolved. Dissolve the residue in 
300 cc. of water, pass hydrogen sulphide gas into 
the solution at 70° C. until the copper is completely 
precipitated, filter, concentrate the filtrate, expel the 
sulphuric acid on the sand-bath, and ignite the 
residue. The weight of the latter should not exceed 
0.002 gm. , 

Arsenic. — Dissolve 10 gm. of copper in 60 cc. of nitric 
acid (sp. gr. 1.3), add to the solution 15 ce. of concentrated 
sulphuric acid (sp. gr. 1.84), evaporate the solution on the 
water-bath as far as possible, and then heat the residue on 
the sand-bath until vapors of sulphuric acid are evolved. 
When cold, dissolve the residue in 100 ee. of water. 

Set a Marsh apparatus in operation, using 50 gm. of arsenic- 
free, granulated zinc, and dilute (1:5) sulphuric acid, then 
introduce the copper sulphate solution in small quantities at 
a time, and maintain the flow of gas for about two hours. 
No deposit of arsenic should be visible in the reduction tube 
within this time. 


96 CHEMICAL REAGENTS 


COPPER CHLORIDE, CUPRIC 


(CopPpER DICHLORIDE) 
CuCl, + 2H:O. Mol. Wt. 170.53: 
Green, hygroscopic crystals, easily soluble in water, alcohol, 


and ether. 
TESTS OF PURITY 


Substances Insoluble in Alcohol. — The solution of 5 gm. 
of copper chloride in 5 cc. of water should not be rendered 
turbid on mixing with 5 ec. of 95 per cent alcohol. 

Sulphates. — Dissolve 1 gm. of copper chloride in 20 cc. of 
water, and add 0.5 cc. of hydrochloric acid, followed by 
barium chloride solution. No turbidity should ensue within 
five minutes. 

Salts of Alkali Metals. — Dissolve 3 gm. of copper chloride 
in 100 ce. of water, add 5 cc. of hydrochloric acid, and into 
the solution, maintained at about 70° C., pass hydrogen 
sulphide gas, until the copper is completely precipitated; — 
filter, evaporate the filtrate to dryness, and ignite the residue. 
The weight of the latter should not exceed 0.002 gm. 

Iron. — The test is carried out as described under Copper 
and Ammonium Chloride. 

Arsenic. — Introduce 20 gm. of arsenic-free, metallic zine 
into the generating flask of a Marsh apparatus, and start 
the hydrogen by adding dilute (1:5) sulphuric acid. Dis- 
solve 1 gm. of copper chloride in 20 ce. of water, introduce 
the solution in small quantities at a time into the Marsh 
apparatus, and maintain a slow stream of gas for about one 
hour. No deposit of arsenic should be visible in the reduction 
tube of the apparatus within this time. 


CHEMICAL REAGENTS 97 


COPPER CHLORIDE, CUPROUS 


(CoppER MONOCHLORIDE) 
CuCl. Mol. Wt. 198.1. 

A white, crystalline powder, insoluble in water, but soluble 
in concentrated hydrochloric acid and in ammonia water. 

The quality of cuprous chloride may be judged from its 
appearance. The preparation should be white, but not 
ereen nor brown.* Both the hydrochloric acid and the 
ammoniacal solutions should rapidly and freely absorb 
carbon monoxide. 


COPPER OXIDE 


(CupRIC OXIDE) 
CuO. Mol. Wt. 79.6. 

Copper oxide is used in ultimate organic analysis, in the 
form of fine powder or coarse granules, and also in the form 
of wire. 

TESTS OF PURITY 

Nitrates, Chlorides, and Carbon Dioxide.— On _ heating 
100 gm. of copper oxide, and passing over it a stream of 
moist air freed from carbonic acid, no vapors should be given 
off which redden litmus paper, or render;lime water turbid. 

Substances not Precipitated by Hydrogen Sulphide (Iron, 
etc.). — Dissolve 2 gm. of copper oxide in 10 ce. of hydro- 
chloric acid (sp. gr. 1.19), dilute with water to 100 cc.; ignite 
the insoluble residue, the weight of which should not exceed 
0.005 gm, Pass hydrogen sulphide gas into the solution at 
about 70° C., until the copper has completely precipitated, 
filter, evaporate the filtrate on the water-bath, and ignite 
the residue. The weight of the latter should not exceed 
0.02 gm. , 

Sulphates. — Dissolve 1 gm. of copper oxide in 5 ce. of 


* Cuprous chloride soon acquires a green color in air. 


98 CHEMICAL REAGENTS 


hydrochloric acid (sp. gr. 1.19), dilute with water to 50 cc., 
and add barium chloride solution. No immediate turbidity 
should appear. 

Calcium. — Digest 20 gm. of copper oxide with a mixture | 
of 5 ec. of nitric acid and 95 ec. of water for about fifteen 
minutes, shaking frequently; filter, precipitate the copper in 
the filtrate completely by passing hydrogen sulphide gas, and 
filter again. Evaporate the filtrate on the water-bath to 
about 20 cc., add ammonia water in excess, filter once more, 
and to the filtrate add ammonium oxalate solution. No 
immediate turbidity should be produced. . 


COPPER SULPHATE 


(Cupric SULPHATE) 
CuSO, + 5H,O. Mol. Wt. 249.74. 


Blue, transparent crystals, slightly efflorescent in dry air, 
soluble in 3.5 parts of cold, and’in 1 part of boiling, water; 
insoluble in alcohol. The aqueous solution is acid to litmus 
paper. 

TESTS OF PURITY 

Salts of the Alkalis, Earths, etc. — Dissolve 3 gm. of copper 
sulphate in 100 cc. of water, add 5 cc. of hydrochloric acid, 
and into the solution, maintained at about 70° C., pass 
hydrogen sulphide gas until the copper is completely precipi- 
tated. On evaporating the filtrate to dryness, and igniting 
the residue, the weight of the latter should not exceed 0.001 
om. 

Iron. — To the solution of 5 gm. of copper sulphate in 
25 ec. of water, add 2 ce. of nitric acid (sp. gr. 1.3), and 
heat the mixture to boiling. Then add 20 ce. of ammonia 
water, pour the liquid through an ashless filter, wash the 
latter with ammoniacal water until perfectly free from 
copper, and then incinerate and ignite the filter together 


CHEMICAL REAGENTS 99 


with any precipitate it may contain. The weight of the 
residue should not exceed 0.001 gm. 


COPPER AND AMMONIUM CHLORIDE 


(AMMONIO-CUPRIC CHLORIDE) _ 
CuCl, -2(NH,Cl) + 2H:O. Mol. Wt. 277.57. 
Blue crystals, giving with water a clear solution slightly 


acid to litmus paper. 
TESTS OF PURITY 


Free Acids. — A solution of 30 gm. of copper and ammo- 
nium chloride in 100 cc. of water must be perfectly clear. 
On introducing into the solution several pieces of piano wire, 
the latter should dissolve with the deposition of copper, but 
without any evolution of gas. 

Sulphates. — Dissolve 1 gm. of copper and ammonium 
chloride in 20 ec. of water, and add 0.5 cc. of hydrochloric 
acid, followed by barium chloride, solution. No turbidity 
should be produced within five minutes. 

Salts of the Alkalis, Earths, etc. — Dissolve 3 gm. of copper 
and ammonium chloride in about 100 cc. of water, add 
5 ec. of hydrochloric acid, pass hydrogen sulphide gas into 
the solution at about 70° C., until the copper is completely 
precipitated; filter, evaporate the filtrate, and ignite the 
residue. The weight of the latter should not exceed 0.002 
em. 
Iron. — Dissolve 5 gm. of copper and ammonium chloride 
in 25 ec. of water, add 2 cc. of nitric acid (sp. gr. 1.3), heat 
to boiling, then add 20 cc. of ammonia water and pour the 
liquid through an ashless filter. Wash the latter with 
ammoniacal water until perfectly free from copper; incin- 
erate and ignite the filter together with any precipitate it 
may contain. The weight of the. residue should not exceed 
0.002 gm. 


100 CHEMICAL REAGENTS 


DIPHENYLAMINE * © 
(CoHs)2NH. Mol. Wt. 169.12. 


White, monoclinic crystals, insoluble in water, but easily 
soluble in aleohol, ether, and benzene. Diphenylamine melts 
at 54° C. and boils at 302° C. 


TESTS OF PURITY 


Nitric Acid. — 0.2 gm. of diphenylamine should dissolve in 
20 cc. of pure concentrated sulphuric acid with 2 ce. of water, 
and yield a colorless solution. Should a blue color develop, 
the sulphuric acid should be tested with brucine for the 
possible presence of nitric acid. 

Aniline. — On pouring 1 gm. of powdered diphenylamine 
into 20 cc. of a chlorinated lime solution, the liquid should 
not acquire a violet color. 


* The diphenylamine solution, used as a reagent, is prepared by dis- 
solving 0.5.gm. of diphenylamine in 100 cc. of pure, concentrated sulphuric 
acid (free from nitric acid) and 20 cc. of water. According to G. Lunge 
[Ztschr. angew. Chem., 7, 345 (1894); J. Chem. Soc., 66, II, 398 (1894)], 
the reagent is employed as follows: 

To test for nitric or nitrous acid, introduce about 5 cc. of the reagent 
solution into a test tube, and overlay it with the liquid to be examined. 
If the latter is specifically heavier than the reagent solution, the dipheny- 
lamine solution is to be overlaid upon the liquid. 

Regarding the increased sensitiveness of the nitric-acid reaction with 
diphenylamine in water analyses, see R. Cimmino, Ztschr. anal. Chem., 
38, 429 (1899); J. Chem. Soc., 70, II, 805 (1899). 


CHEMICAL REAGENTS 101 


ETHER 


(ErHyL ErHEr) 


i 
ETHER, SP. GR. 0.720 


A clear, colorless, mobile liquid of specific gravity 0.720,* 
boiling at 34 to 36° C. Ether should not redden moist blue 
litmus paper. Filter paper which has been moistened with 
ether should have no odor when dry. 


TESTS OF PURITY 


Residue. — On allowing 20 cc. of ether to evaporate spon- 
taneously in a glass dish, the residue must have no odor, 
and should not redden or decolorize blue litmus paper; and 
it must be completely volatilized on warming on the water- 
bath. : 

Ethyl Peroxide, Hydrogen Peroxide, and Ozone. — On vig- 
orously shaking 10 cc. of ether with 1 ec. of 1:10 aqueous 
potassium iodide solution in a completely filled glass-stop- 
pered bottle, neither the ether nor the potassium iodide 
solution should acquire a color after standing one hour in 
the dark. 

Aldehydes. — On covering pieces of potassium hydroxide 
the size of a pea with the ether, and setting aside in the 
dark for one half hour, the liquid must not acquire a yellow 
color. 

Sulphur Compounds. — On shaking 20 ec. of ether with a 
globule of mercury for two minutes in a glass-stoppered 

*It must be remembered that ether is apt to absorb moisture from the 


air, particularly when poured from one vessel into another, acquiring in 
consequence a higher specific gravity. 


102 . CHEMICAL REAGENTS 


bottle, the bright surface of the metal must not be tarnished; 
nor should a black precipitate form. 

Water. — On shaking 20 cc. of ether in a stoppered flask 
with 1 gm. of anhydrous copper sulphate, the latter should 
not acquire a green or blue color. 


II 


ETHER, ANHYDROUS, DISTILLED OVER SODIUM 
TESTS OF PURITY 


In addition to the tests given above, this preparation must 
answer the following requirement: 

On introducing 15 cc. of ether into a dry, glass-stoppered 
flask with a freshly-cut piece of sodium the size of a pea, 
only a very slight evolution of gas should take place, and 
the bright metallic surfaces of the sodium should not com- 
pletely lose their luster within six hours. 


_ FURFURAL 


(FURFUROL) 
C;H.O>. Mol. Wt. 96.03. 


When freshly prepared, furfural is a clear, colorless liquid, 
which rapidly acquires a yellow color on exposure to light 
and air. Furfural has a specific gravity of 1.165 to 1.166, 
boils at 158 to 160° C., and is soluble in 12 parts of cold 
water. It is very easily soluble in alcohol and in ether. 


Norn. — Regarding the quantitative determination of furfural, see 
W. E. Stone, Ztschr. anal. Chem., 40, 550 (1901); J. Anal. Appl. Chem., 
5, 421 (1895). W. Cormack, Ztschr. anal. Chem., 43, 256 (1904); J. Chem. 
Soc., 77, 990 (1900). Merck’s Reagentien-Verzeichnis, p. 19 (1903); 
Lewkowitsch, Chem. Technol. and Anal. Oils, Fats, and Waxes, 3 ed.. 
Vol. II, p. 542 (1904). Merck’s Reagentien-Verzeichnis, pp. 129, 157 
(1903); H. Schiff, J. Chem. Soc., 52, 571 (1887). Woltering, Pharm. 
Ztschr. f. Russl., 31, 526 [Ztschr. anal. Chem., 36, 410 (1897)]. 


CHEMICAL REAGENTS 103 


GALLEIN, LIQUID 
(GALLEIN) 


A pale brown coloring matter, consisting of pyrogal- 
lolphthalein. Gallein in alcoholic solution is used as an 
indicator. : 3 

GLYCERIN 


(GLYCEROL) 


I 
GLYCERIN, SP. GR. 1.250 


A clear, colorless, odorless liquid, neutral in reaction, 
soluble in all proportions in water and in alcohol. Insoluble 
in ether and chloroform. Specific gravity not less than 1.250. 
It contains at least 95 per cent of absolute glycerin, C,H,O.. 


TESTS OF PURITY 


Arsenic. — On mixing 1 cc. of glycerin with 3 cc. of stan- 
nous chloride solution, the mixture should not darken within 
one hour. 

Free Acids and Bases. — On diluting 10 cc. of glycerin 
with 50 cc. of water, the solution should not affect red or 
blue litmus paper. 

Inorganic Matter. — On boiling 5 cc. of glycerin in an open 
dish and then gently igniting, the glycerol should be vola- 
tilized completely, leaving only a dark stain which should 
disappear on being more strongly heated. 

Substances which Reduce Ammoniacal Silver Nitrate Solu- 
tion. — On heating a mixture of 1 cc. of glycerin and 1 cc. 
of ammonia water on the water-bath to 60° C., and then 
immediately adding 3 drops of silver nitrate solution, neither 


104 CHEMICAL REAGENTS 


a coloration nor a brownish-black precipitate should develop 
within five minutes. 

Fatty Acids. — On gently warming 1 cc. of glycerin with 
1 ec. of 16 per cent sulphuric acid, no unpleasant, rancid 
odor should develop. 

Hydrochloric Acid (Chlorides). — 5 cc. of glycerin diluted 
with 25 cc. of water should exhibit at most a slight, opa- 
lescent turbidity on the addition of silver nitrate solu- 
tion. 

Sulphuric and Oxalic Acids. — The solution of 5 gm. of 
glycerin in 25 cc. of water should not be affected by barium 
chloride solution nor by calcium chloride solution. 

Heavy Metals. — On diluting 5 cc. of glycerin with 25 cc. 
of water and adding hydrogen sulphide water, no change 
should appear. 

Calcium. — 5 cc. of glycerin dissolved in 25 cc. of water 
should not be affected by the addition of ammonium oxalate 
solution. 

Sugars. — 5 cc. of glycerin are mixed with 50 cc. of water 
and a few drops of hydrochloric acid, heated thirty minutes . 
on a water-bath, then 10 cc. of the hot liquid are made alka- 
line with sodium hydroxide and mixed with 1 cc..of Fehling’s 
solution. No yellowish-red cloud or precipitate should appear 
within six hours. 

Readily Carbonizable Matter. —5 cc. of glycerin mixed 
‘with an equal volume of concentrated sulphuric acid, and 
allowed to stand one hour, should not become darker than 
yellow. 


II 
GLYCERIN, SP. GR. 1.23 


A clear, colorless, odorless liquid of neutral reaction. Its 
specific gravity is 1.225-1.235. © 


CHEMICAL REAGENTS 105 


TESTS OF PURITY 


The tests for arsenic, heavy metals, chlorides, substances 
which reduce ammoniacal silver nitrate, free acids and 
bases, oxalic, sulphuric and fatty acids, and inorganic matter, 
are to be made in the manner described under Glycerin, 
sp. gr. 1.250. 

The following additional test is also to be made: 

Ammonium Compounds and Organic Bodies Such as Occur 
in Unpurified Glycerin. — On heating 1 cc. of glycerin with 
1 cc. of sodium hydroxide solution, no ammonia should be 
evolved (to be detected by means of moistened litmus paper) ; 
nor should a color develop nor an odor resembling that of 
glue. 


GUAIACIN ACCORDING TO SCHMITT * 


Guaiacin is a brownish, amorphous powder, obtained by a 
special method from guaiac wood. It is soluble in alcohol, 
is colored blue by oxidizers, is far more sensitive than guaiac 
resin, and serves as an excellent reagent for oxidases. Guai- 
acin is used in the form of a 5 per cent alcoholic solution, 
which keeps well in completely in dark-colored, well- 
stoppered bottles. 


HEMATEIN 
CieHi20¢. Mol. Wt. 300.09. 


Hematein occurs in reddish-brown plates, presenting a 
yellowish-green metallic luster. 100 parts of water at 20° C. 
dissolve 0.06 part of hematein. It is difficultly soluble in 
ether and in alcohol, and insoluble in chloroform and benzene; 
but it is soluble in ammonia water with brownish-violet 

* Le Bois de Gajac, Thése de Nancy. 1875. Report on the Advance- 


ments of Pharmaceutical Chemistry and Therapeutics, E. Merck, p. 73, 
1902. 


106 CHEMICAL REAGENTS 


color, and in dilute sodium hydroxide solution, producing a 
bright-red color. 
HEMATOXYLIN 
“CreHuOc + 3H.0. Mol. Wt. 356.16. 


Colorless, or pale-yellow, tetragonal prisms, melting at 
100 to 120° C. with loss of water. On slowly cooling a solu- 
tion saturated at boiling heat, hematoxylin crystallizes at 
times in the form of rhombic crystals containing one mole- 
cule of water of crystallization. Hematoxylin is but slightly 
soluble in cold water and in ether, but is more soluble in 
borax solution and in hot water, and is easily soluble in 
alcohol. On exposure to light it gradually acquires a red 
color, and then dissolves to form yellow solutions. In 
ammonia water hematoxylin dissolves and yields a purple 
solution. Hematoxylin is used as an indicator in 0.5 per 
cent alcoholic solution. 


Norr. — Regarding the use of hematoxylin as an indicator in the 
titration of alkaloids, see C. Kippenberger, Ztschr. anal. Chem., 39, 201 
(1900); J. Chem. Soc., 78, II, 637 (1900). J. Messner, Ztschr. angew. 
Chem., 16, 444 (1903); J. Chem. Soc., 84, II, 519 (1903). 


HIDE POWDER 


White or yellowish-white, woolly powder, prepared from 
the best quality of hide from which the hair has been re- 
moved with lime and which has been thoroughly washed. 
Hide powder should have but a slight odor and should be 
specially free from odors of decomposition products. It is 
used for tannin. determination. 


TEST OF PURITY 
Determination of the Water-Soluble Constituents.* — In- 


* As the quantity of water-soluble constituents in the various hide 
powders varies greatly, it is always necessary, before using a hide powder 
for tannin determinations, to determine the quantity of soluble constit- 
uents by a blank test according to the method described here. 







JE, BRARE 
f OF THE 
UNIVERSITY 
OF é 


b r A 
~CALIFORNIS 





CHEMICAL REAGENTS 107 


troduce 5 gm. of the hide powder into a bell-filter, as de- 
scribed by. Procter (see Lunge, Chem.-tech. Untersuch.- 
Meth., 5 ed., 3, 715 (1905); Allen, Com. Organ. Anal., 3 ed., 
Vol. III, Pt. I, p. 83 (1900)). Then suspend the filter in a 
beaker of about 150 to 200 cc. capacity, fix the siphon, by 
means of a clamp, so that the bell-filter almost reaches the 
bottom of the vessel, and then pour into the beaker a small 
quantity of water in order to moisten the hide powder by 
capillarity. After the powder has become moist, which re- 
quires about an hour, the beaker is filled, and suction care- 
fully applied to the siphon until the filtrate begins to drop 
slowly. The filtration of 90 to 100 cc. requires about one 
and a half to two hours. The 30 ce. first siphoned off are 
rejected; the next 50 ce. are evaporated to dryness on the 
water-bath. The residue from the evaporation is then dried 
to constant weight in an air-bath at 100 to 105° C. The 
weight of this residue, conforming to the requirements laid 
down by the International Conference of Chemists for Leather 
Industries, should not exceed 0.005 gm. 


HYDROGEN PEROXIDE, 30% 


(PERHYDROL) 
H:02. Mol. Wt. 34.01. 


A colorless liquid of specific gravity 1.115 to 1.119, con- 
taining about 30 per cent by weight of hydrogen peroxide.* 
The solution is acid to litmus paper. 


* The solution, containing 30 per cent, by weight, of hydrogen peroxide, 
is also designated as “‘100 volumes hydrogen peroxide,” because this 
solution is capable of yielding 100 times its volume of free oxygen. 

+ The acid reaction is entirely due to the high content of hydrogen 
peroxide. If it is desired to ascertain whether the acidity is due alsoto 
the presence of acids, the hydrogen peroxide is first decomposed by means 
of a small piece of platinum sponge. 


108 CHEMICAL REAGENTS 


TESTS OF PURITY 


Sulphuric Acid. — Dilute 1 cc. of the hydrogen peroxide 
with 20 cc. of water, add 0.5 ec. of hydrochloric acid, heat to 
boiling, and add barium chloride solution. No precipitate 
of barium sulphate should form on standing twelve hours. 

Residue on Evaporation (Sulphuric and Phosphoric Acids, 
etc.). — 10 cc. of the hydrogen peroxide, when heated on the 
water-bath, should completely volatilize and leave no weigh- 
able residue. 

Oxalic Acid. — The solution of 2 cc. of hydrogen peroxide 
in 10 ce. of water should not become turbid on the addition 
of calcium chloride solution. 7 

Hydrochloric Acid. — The solution of 1 cc. of hydrogen 
peroxide in 20 cc. of water with 1 cc. of nitric acid should 
not become turbid on the addition of a few drops of silver 
nitrate solution. | 

Hydrofluoric Acid. — Evaporate 10 cc. of hydrogen per- 
oxide with a few drops of sodium hydroxide solution, transfer 
the concentrated liquid to a watch glass, evaporate to dryness 
on the latter, pour concerrtrated sulphuric acid. over the 
residue, and allow the whole to stand two to three hours in 
a warm place. After washing off the glass, no etching should 
be visible. 

Phosphoric Acid. — Concentrate 5 ec. of hydrogen peroxide 
on the water-bath, take up any residue with 3 cc. of water, 
add 1 cc. of magnesia mixture and 3 cc. of ammonia water. 
No precipitation should take place on standing twelve hours. 

Quantitative Determination. — Weigh off 1 gm. of hydrogen 
peroxide in a graduated flask of 100 cc. capacity, and fill 
with water to the mark. Dilute 20 cc. of this liquid with 
50. ce. of water, add 40 cc. of 16 per cent sulphuric acid, and 
titrate with decinormal potassium permanganate. At least 
35 ec. should be required to produce the end-point. 


CHEMICAL REAGENTS 109 


1 cc. of decinormal KMnO, = 0.0017008 gm. of H,0,, log. 
23065. 
HYDROGEN SULPHIDE WATER 


A clear, colorless liquid, having a strong odor of hydrogen 
sulphide, gas, and affording a voluminous precipitate of 
sulphur on the addition of ferric chloride solution. Hydrogen 
sulphide water has an acid reaction to litmus paper. 


HYDROXYLAMINE HYDROCHLORIDE 


NH.OH-HCl. Mol. Wt. 69.52. 


Dry, colorless crystals, soluble in 1 part of water and in 
15 parts of alcohol, and also in glycerin. The aqueous solu- 
tion is acid to litmus paper. 


TESTS OF PURITY 


Non-volatile Matter. — 1 gm. of hydroxylamine hydrochlo- 
ride, heated on platinum foil, should volatilize and leave no 
residue. 

Ammonium Chloride. — The 1:20 alcoholic solution should 
afford no precipitate on adding platinic chloride solution. 

Sulphuric Acid. — On adding barium chloride solution to 
20 cc. of a 1:10 aqueous solution of hydroxylamine hydro- 
chloride, no precipitate of barium sulphate should form — 
within twelve hours. | 

Iron. — 10 cc. of the 1:10 aqueous solution are boiled 
two or three minutes with 1 cc. of 15 per cent potassium 
hydroxide solution. While still hot, acidify with 1 cc. of 
strong nitric acid and subsequently add an excess of potas- 
sium sulphocyanate solution. No red color should appear. 

Quantitative Determination. — Dissolve 1 gm. of hydroxyl- 
amine hydrochloride in 30 ce. of water, and titrate the solution 
with normal potassium hydroxide to permanent redness, 
using phenolphthalein as indicator. 


110 CHEMICAL REAGENTS 


1 cc. of normal KOH = 0.06952 gm. of NH,OH * HCl, log. 
84211. 


INDIGO 


I 
SYNTHETIC INDIGO 


A fine, dark-blue powder, containing at least 95 per cent 


of indigo blue. 
TESTS OF PURITY 


Ash. — On heating 1 gm. of indigo in a platinum crucible, 
- beautiful purple-red vapors are evolved, and a residue is left, 
the weight of which, after ignition, should not exceed 0.01 gm. 
Moisture. — On drying 1 gm. of indigo at 100° C. to con- 
stant weight, the loss of weight should not exceed 0.01 gm. 
Quantitative Determination ef Indigo Blue (Indigotin *). — 
Place 1 gm. of indigo in a beaker of about 50 cc. capacity, 
cover it with 8 cc. of fuming sulphuric acid, containing 8 to 
10 per cent of sulphuric anhydride, and warm the mixture 
on the sand-bath at 50 to 60° C., stirring frequently. The 
indigo will be dissolved in about one to two hours. Rinse 
the solution into a liter flask, and fill with water to the mark. 
Shake thoroughly, and transfer 100 cc. of the solution into a 
porcelain dish, add 400 cc. of water and 50 cc. of dilute 
sulphuric acid (1:10), then titrate immediately with deci- 
normal potassium permanganate. At first no change in the 
dark-blue color is noted, but gradually the color passes 
through green into light yellow. This point (and not the 


* A perfectly unobjectionable method of assaying indigo is not known 
at present. The method here described frequently gives results that are 
too high. The results, however, are satisfactory for fine grades of indigo, 
which rarely contain foreign organic compounds. In this method, how- » 
ever, indigo red is determined along with the indigo blue. 


CHEMICAL REAGENTS 111 


incipient red color) is the sharp and distinctly visible end- 
point of the titration. 
1 cc. of decinormal KMnO, = 0.007415 gm. of indigotin, 
log. 87011. 
IT 


VEGETABLE INDIGO 


Dark-blue, light pieces, which, on being rubbed with a 
horn spoon, or other hard substances, exhibit a coppery 
metallic luster. Good vegetable indigo has a lower specific 
gravity than water, hence it floats on the latter. It should 
contain at least 60 per cent of indigo blue. 


TESTS OF PURITY 


Ash. — 1 gm. of indigo should not leave more than 0.12 gm. 
of ash. 

Moisture. — On drying 1 gm. of indigo to constant weight 
at 100° C., the loss in weight should not exceed 0.06 gm. 

Quantitative Determination of Indigo Blue (Indigotin). — 
This test is to be carried out as detailed under Synthetic 
Indigo. : 
INDIGOTIN 


(INpIGo BLUE) | 
CicHioN202. Mol. Wt. 262.08. 

Purple, rhombic crystals with coppery luster, or dark-blue 
powder with a reddish tint, which, on pressure or rubbing, 
exhibits a coppery luster. Indigo blue is insoluble in water, 
alcohol, ether, dilute acids, and alkalies. It dissolves in 
15 parts of concentrated sulphuric acid, or 5 parts of fuming 
sulphuric acid, with the formation of indigo sulphonic acids. 


TESTS OF PURITY 


Ash. —1 gm. of indigotin, on ignition, should yield a residue 
weighing not more than 0.0015 gm. 


112 CHEMICAL REAGENTS 


Moisture. — On drying 1 gm. of indigotin at 100° C. to 
constant weight, the loss of weight should not exceed 0.005 
om. 

Quantitative Determination. — This is to be carried out as 
described under Synthetic Indigo. 


IODEOSIN 


(TETRAIODOFLUORESCEIN) 
CooHs1.0s. Mol. Wt. 835.94. 


A scarlet-red, crystalline powder, yielding with alcohol a 
deep-red, and with ether a yellowish-red, solution. Iodeosin 
is insoluble in water containing a trace of hydrochloric acid. 
The solution used as an indicator is prepared by dissolving 
1 gm. of iodeosin in 500 ce. of alcohol. 


TEST OF SENSITIVENESS 


Introduce 100 cc. of water, containing 5 drops of the above 
iodeosin solution, into a colorless, glass-stoppered flask, and 
then overlay it with 30 cc. of ether. Then run in by drops, 
from a burette, centindrmal hydrochloric acid solution, vig- 
orously shaking after the addition of each drop, until the 
aqueous layer just becomes colorless. Now add 5 drops 
more of the iodeosin solution. After shaking again, the 
aqueous layer must not acquire a pink color; or, should it 
do so, the color must disappear on the addition of 1 drop of 
centinormal hydrochloric acid. 


Notr. — Regarding the use of iodeosin for the estimation of alka- 
loids, see C. Kippenberger, Ztschr. anal. Chem., 39, 205 (1900); J. Chem. 
Soc., 78, II, 637 (1900). Merck’s Berichte, pp. 9, 32 (1900); Merck’s 
Annual Report, pp, 13, 37 (for the year 1900). 


CHEMICAL REAGENTS | 113 


IODINE 


(IopINE RESUBLIMED) 
I. Atomic Wt. 126.97. 


Blackish-gray, dry, rhombic plates or scales, with a metallic 
luster, easily soluble in alcohol, ether, and chloroform. Iodine 
dissolves in about 5000 parts of water, and is very freely 
soluble in an aqueous solution of potassium iodide. The 
preparation contains 99.98 to 100 per cent of I. 


TESTS OF PURITY 


Non-volatile Matter.— On cautiously heating 1 gm. of 
iodine in a porcelain dish, no weighable residue should remain. 

Cyanogen, Chlorine, and Bromine. — Shake 0.5 gm. of 
powdered iodine with 20 cc. of water, and filter. To 10 ce. 
of the filtrate, add, drop by drop, decinormal sodium thio- 
sulphate solution until decolorized, then add a granule of 
ferrous sulphate, 1 drop of ferric chloride solution and 2 ce. 
of sodium hydroxide solution. Warm to about 60° C., and 
add 10 ec. of hydrochloric acid. The liquid should not 
acquire a blue color. Filter, and to 10 ce. of the filtrate add 
1 cc. of ammonia water, 5 drops of silver nitrate solution, 
and again filter. On adding to the filtrate 2 cc. of nitric 
acid no precipitate, and not more than an opalescent turbid- 
ity, should develop.* 

Quantitative Determination. — Dissolve 0.2 gm. of iodine 
with 1 gm. of potassium iodide in 50 cc. of water, and titrate 
with decinormal sodium thiosulphate.t 

1 cc. of decinormal Na,S,O, = 0.012697 gm. of I, log. 10369. 


* The filtrate contains traces of dissolved silver iodide; hence, on 
acidulating with nitric acid some opalescence always occurs. 

+ The titer of the decinormal sodium thiosulphate should be controlled 
by means of potassium biniodate. 


114 CHEMICAL REAGENTS 


IODINE WATER 


A saturated aqueous solution, containing about 0.2 gm. of 
iodine in 1000 ce. 


TEST OF STRENGTH 


Titrate 100 ec. of iodine water with decinormal sodium 


thiosulphate solution. 
1 ce. of decinormal Na.S,0, = 0.012697 gm. of I, log. 10369. 


IRON 
Fe. Atomic Wt. 55.9. 


Metallic iron is used in the analytical laboratory in the 
form of thin, polished wire (piano wire), or gray powder 
obtained by reduction with hydrogen (iron by hydrogen), 
and also in the form of the ordinary gray, lustrous powdered 


iron. 
I 


IRON WIRE 
(P1ANo WIRE) 


Iron wire serves chiefly for the standardization of potas- 
sium permanganate solutions. It was formerly believed, 
without further consideration, that the wire contained 99.6 
to 99.8 per cent of pure, active iron. ‘Treadwell, however, has 
shown that the various kinds of wire exhibit a decidedly 
variable value towards potassium permanganate solution, and 
that several exhibit a value corresponding to over 100 per 
cent of Fe, which statement is fully confirmed by Lunge. 
The explanation of this lies in the presence of carbon in the 
wire, principally as carbide of iron, which, upon dissolving 
in acid, becomes converted into hydrocarbons, exerting a 
marked reducing action on the permanganate. 

Notwithstanding this, iron wire is a convenient, unalterable, 


CHEMICAL REAGENTS 115 


and also perfectly reliable substance for standardizing per- 
manganate solutions, if we have once. ascertained its effective 
value compared with potassium permanganate solution, the 
titer of which has been accurately determined by means of 
some other standard. _ 

For a satisfactory means of fixing the titer of perman- 
ganate solution, sodium oxalate may be recommended (see 
Sodium Oxalate, According to Sérensen). Or * starting with 
sodium bicarbonate, then by drying at about 300° C., thus 
obtaining sodium carbonate, preparing a standard solution 
of this, from this preparing a solution of fifth normal hydro- 
chloric acid, from this a solution of fifth normal potassium 
hydroxide, from this a solution of oxalic acid, and finally a 
solution of the permanganate. Where a gasvolumeter is at 
hand, the titer may also be ascertained with hydrogen perox- 
ide, according to the nitrometer method. (G. Lunge, Chem.- 
tech. Untersuch.-Meth., 5 ed., 1, 127 (1904); J. Chem. Soc., 
58, 1468 (1890).) 

II 
IRON BY HYDROGEN 
(Repucep Iron) 

A gray, lusterless, fine powder, containing at least 90 per 
cent of Fe. 

TESTS OF PURITY 

Solubility in Acids; Carbon and Silica. — 10 gm. of reduced 
iron should dissolve almost completely in a mixture of 20 ce. 
of sulphuric acid (sp. gr. 1.84) and 200 cc. of water. Any 
insoluble residue should be filtered off, and when dried at 


100° C. its weight should not exceed 0.05 gm. 
Sulphides. — Pour a mixture of 10 ec. of hydrochloric acid 


*G. Lunge, Ztschr. angew. Chem. 17., 267, (1904); J. Chem. Soc., 86 
II, 289 (1904). 


116 CHEMICAL REAGENTS 


and 10 ce. of water over 1 gm. of reduced iron in a test tube. 
Filter paper moistened with solution of lead acetate should not 
be darkened in color on exposure to the liberated hydrogen 
for ten seconds. 

Sodium Carbonate. — On shaking 5, gm. of reduced iron 

with 50 cc. of water and filtering, the filtrate should not 
turn red litmus paper blue; and on evaporation it should 
leave no residue. 
_ Nitrogen. — Dissolve 10 gm. of reduced iron in a mixture 
of 20 cc. of concentrated sulphuric acid (sp. gr. 1.84) and 
200 cc. of water, with the aid of heat. Allow to cool, and 
when cold add 100 cc. of sodium hydroxide solution (sp. 
er. 1.3), and distil off about 50 cc., collecting the distillate 
in a receiver containing about 20 ec. of water and 2 to 3 ce. 
of decinormal hydrochloric acid. Titrate the distillate with 
decinormal potassium hydroxide, using methyl orange as 
indicator. The ammonia should not have neutralized more 
than 0.2 ec. of the acid. 

Arsenic. — Pour 10 cc. of hydrochloric acid over a mixture 
of 1 gm. of reduced iron and 1 gm. of potassium chlorate, 
and when the reaction has subsided, heat until all free chlo- 
rine has been expelled. On now adding 15 cc. of stannous 
chloride solution to 5 cc. of the filtrate, a dark coloration 
should not develop within one hour. 

Quantitative Determination. — Introduce into a graduated 
flask of 100 ec. capacity 1 gm. of reduced iron, 10 gm. of 
finely powdered mercuric chloride, and 50 cc. of boiling water. 
Place the flask on wire gauze, heat over a small flame, boil for 
’ about five minutes with frequent shaking; then immediately 
fill the flask to the mark with cold, boiled water. Cool the 
mixture to 15° C., add water to the mark, shake thoroughly, 
and, tightly stoppering the flask, set it aside to deposit. 
Now filter, and to 10 cc. of the filtrate add immediately 10 cc. 
of 16 per cent sulphuric acid, and titrate with decinormal 


CHEMICAL REAGENTS 117 


potassium permanganate until a faint red color persists. 
At least 16 cc. of the permanganate solution should be re- 
quired. 

For the purpose of control, dissolve in the slightly red 
liquid 2 gm. of potassium iodide, allow to stand for one hour 
in the stoppered flask at 20° C., and titrate with decinormal 
sodium thiosulphate solution, using starch solution as the 
indicator. 

_ lce. of decinormal KMnO, or 1 cc. of decinormal Na,S,0, 
= 0.00559 gm. of Fe, log. 74741. 


Ill 
IRON POWDER 


A fine, heavy, gray powder with metallic luster, and con- 
taining at least 98 per cent of Fe. 


TESTS OF PURITY 


Solubility in Acids; Carbon, Silica, and Sulphur. — 10 gm. 
of powdered iron should dissolve almost completely in a 
mixture of 20 ec. of concentrated sulphuric acid (sp. gr. 1.84) 
and 200 cc. of water. Any insoluble residue should be filtered 
off and dried at 100° C. Its weight should not exceed 0.005 
gm. The gas evolved during solution should not impart 
more than a brownish color within five seconds to strips of 
filter paper moistened with lead acetate solution. 

Nitrogen and Arsenic.— These tests are carried out as 

detailed under Iron by Hydrogen. 
_ Copper, Zinc, and Lead. — Dissolve 1 gm. of powdered iron 
in 25 cc. of nitric acid, assisting solution by heating the 
mixture to boiling. Dilute the solution with 25 cc. of water, 
add 30 cc. of ammonia water, and filter. The filtrate should 
not have a blue color; nor should it show any change on the 
addition of hydrogen sulphide water. 


118 CHEMICAL REAGENTS 


Quantitative Determination. — Dissolve 1 gm. of powdered 
iron in about 50 ec. of dilute sulphuric acid, and dilute the 
solution to 100 ec. To 10 ce. of this solution add decinormal 
potassium permanganate solution until the liquid has a slight 
red color, and when the liquid becomes decolorized, which 
may be effected, if necessary, by adding a few drops of 
alcohol, add 2 gm. of potassium iodide. Allow the mixture 
to stand one hour in a closed flask at 20° C., and then titrate 
with decinormal sodium thiosulphate. At least 17.5 ec. 
should be required to combine with the liberated iodine. 

1 cc. of decinormal Na,S,0, = 0.00559 gm. of Fe, log. 74741. 


IRON CHLORIDE, FERRIC 
FeCl; + 6H:O. Mol. Wt. 270.34. 


Yellow, crystalline masses, very deliquescent in air. Ferric 
chloride is easily soluble in water, alcohol, and a mixture of 
aleohol and ether. The solutions are acid to litmus paper. 


TESTS OF PURITY 


Basic Salt and other Material Difficultly Soluble in Water. — 
10 gm. of ferric chloride should completely dissolve in 10 ee. 
of water, and yield a perfectly clear solution. 

Hydrochloric Acid and Chlorine. — On bringing a glass rod, 
moistened with ammonia water, over a few cubic centimeters 
_of a ferric chloride solution (1:1), contained in a watch glass, 
-no cloud should form. On introducing a piece of paper, 
moistened with zinc iodide-starch solution, into the neck of 
a flask containing (1:1) ferric chloride solution, the paper 
should not acquire a blue color within two minutes. 

Arsenic. — A mixture of 1 ec. of ferric chloride solution 
(1:1) and 3 ec. of stannous chloride solution should not 
acquire a darker color within one hour. 

Ferrous Salt. — Add 1 ec. of hydrochloric aad and a few 


CHEMICAL REAGENTS 119 


drops of potassium ferricyanide solution to the 1:20 aqueous 
solution of ferric chloride; no blue color should develop. 

Copper, Nitric Acid, etc. (Alkali Salts, Calcium). — Dilute 
20 ec. of ferric chloride solution (1:1) with 100 ce. of water, 
add 25 ce. of ammonia water, and filter. On evaporating 
50 ec. of the colorless filtrate and igniting the residue, the 
weight of the latter should not exceed 0.001 gm. On mixing 
2 cc. of the filtrate with 2 cc. of concentrated sulphuric acid, 
and overlaying this mixture with 1 cc. of ferrous sulphate 
solution, no brown zone should form at the contact-surfaces 
of the two liquids. 20 cc. of the filtrate acidulated with 
acetic acid should not be affected by potassium ferrocyanide 
solution. 

Sulphates. — Dissolve 10 gm. of ferric chloride in 100 ce. of 
water, add 25 ec. of ammonia water, filter, acidulate the 
filtrate with acetic acid, and add barium chloride solution. 
No precipitate of barium sulphate should form on standing 
twelve hours. 


IRON CHLORIDE, FERRIC, SOLUTION 


A clear, deep yellowish-brown liquid, of specific gravity 
1.280 to 1.282. 100 parts contain 10 parts of Fe = 29 parts 
of FeCl,. 


TESTS OF PURITY 


The tests to be made are those given under Iron Chloride, 
Ferric. But, for each gram of the crystallized ferric chloride, 
3 cc. of the solution of ferric chloride are to be taken. 


IRON CHLORIDE, FERROUS 


FeCl, + 4H.O. Mol. Wt. 198.86. 


_ A pale-green hygroscopic powder, soluble in an equal 
weight of water acidulated with a few drops of hydrochloric 


120 CHEMICAL REAGENTS 


acid, yielding a pale-green solution. Iron chloride is also 
soluble in alcohol. 


TESTS OF PURITY 


Oxychloride. — The solution of 1 gm. of ferrous chloride 
in 1 cc. of water and 2 to 3 drops of hydrochloric acid should 
be pale green or green in color, and should not have any 
yellowish-green tint. On adding 5 cc. of saturated hydrogen 
sulphide water, the solution should show only a very slight 
turbidity, due to the separation of sulphur.* 

Sulphates, Copper, and Alkalies. — Boil for a few minutes 
a solution of 5 gm. of ferrous chloride in 10 ec. of water and 
5 ec. of nitric acid (sp. gr. 1.3), dilute to 120 cc., add 20 ce. 
of ammonia water, and filter; evaporate 50 cc. of the filtrate 
and ignite the residue. The weight of the latter should not 
exceed 0.001 gm. Slightly acidulate 20 cc. of the filtrate 
with hydrochloric acid and add barium nitrate solution. No 
change should appear. 20 cc. of the filtrate acidified with 
acetic acid should show no change upon addition of potassium 
ferrocyanide solution. 

Arsenic. — The solution of 1 gm. of ferrous chloride in 
1 ec. of water, acidulated with a few drops of hydrochloric 
acid, should not acquire a darker color on adding 3 cc. of 
stannous chloride solution and standing one hour. 


IRON SULPHATE, FERROUS 
FeSO, + 7H:O. Mol. Wt. 278. 07. 


Pale, greenish-blue, monoclinic.crystals, soluble in 1.8 parts 
of cold water and in 0.5 part of boiling water; insoluble in 
alcohol and in ether. 


* Small amounts of iron oxychloride are always apt to be present in 
ferrous chloride, even when the latter is most carefully made. 


CHEMICAL REAGENTS 121 


. TESTS OF PURITY 


Substances Insoluble in Water. — The 1: 20 solution, freshly 
prepared with water which has previously been thoroughly 
boiled and then cooled, should be clear and have a greenish- 
yellow color. 

Alkalies. — Add 5 ce. of nitric acid (sp. gr. 1.3) to a solu- 
tion of 5 gm. of ferrous sulphate in 100 cc. of water, and 
boil for several minutes; then add 15 cc. of ammonia water, 
filter; and evaporate the filtrate. The residue ignited should 
not exceed 0.001 gm. in weight. 7 

Copper and Zinc. — Oxidize the solution of 2 gm. of ferrous 
‘sulphate in 50 ec. of water by boiling with 3 cc. of nitric 
acid (sp. gr. 1.3), then add 8 cc. of ammonia water and 
filter : 

(a) 15 ec. of the filtrate should undergo no change on the 
addition of a few drops of ammonium sulphide 
solution. 

(b) Acidify 20 ce. of the filtrate with acetic acid, and add 
potassium ferrocyanide solution; the liquid should 
remain unchanged. 

Quantitative Determination. — Dissolve 1 gm. of ferrous 
sulphate in 50 cc. of well-boiled water, add 10 cc. of dilute 
sulphuric acid, and titrate with decinormal popaean per- 
manganate. 

1 ce. of decinormal KMnO, = 0.027807 em. of FeSO, + 
7H,0, log. 44415. 


IRON SULPHIDE 


(FERROUS SULPHIDE) 
FeS. Mol. Wt. 87.96. 
Dark gray or grayish-black, heavy, hard lumps, soluble in 
diluted hydrochloric or sulphuric acid with the copious evolu- 
tion of hydrogen sulphide. 


122 CHEMICAL REAGENTS 


TEST OF PURITY 


Quantitative Determination. — Place 0.5 gm. of the finely 
powdered iron sulphide in a retort, in the tubule of which is 
fixed a funnel-tube provided with a glass cock. After con- 
necting the retort with a receiver containing 50 to 100 cc. of 
decinormal iodine solution, allow to flow into the retort, 
through the funnel-tube, a mixture of 20 cc. of water and 
20 ec. of dilute sulphuric acid; close the stop-cock, and heat 
to boiling. After the decomposition of the iron sulphide is 
complete, and the hydrogen sulphide has been entirely driven 
off (the iodine solution must not be fully decolorized), deter- 
mine the excess of iodine by means of decinormal sodium 
thiosulphate. 

1 cc. of decinormal I = 0.004398 gm. of FeS, log. 64826. 


IRON AND AMMONIUM SULPHATE, FERRIC 


(FerRIc AMMONIUM SULPHATE; AMMONIO—FERRIC ALUM) 
FeNH,(S80.)2 + 12H,O. Mol. Wt. 482.28. 
Large, pale violet (amethyst colored), transparent, octa- 
hedral crystals, soluble in 2 parts of water and insoluble in 
alcohol. The aqueous solution has an acid reaction. 


TESTS OF PURITY 


Ferrous Salt. — Dissolve 1 gm. of ferric ammonium sul- 
phate in 20 cc. of water, add 1 ec. of hydrochloric acid and 
1 drop of a freshly prepared solution of potassium ferri- 
cyanide. Neither a green nor a blue color should develop. 

Chlorides. — 30 cc. of the 1:20 aqueous solution should 
undergo no change on the addition of 3 cc. of nitric acid 
and silver nitrate solution. 

Zinc and Copper. — To a solution of 2 gm. of ferric am- 
monium sulphate in 50 cc. of water add 10 ce. of ammonia 
water and filter. The filtrate should be colorless, 


e 


CHEMICAL REAGENTS 123 


(a) 20 ce. of the filtrate should show no change on adding 
ammonium sulphide solution. 

(b) On acidifying 20 cc. of the filtrate with acetic acid, 
and then adding potassium ferrocyanide solution, 
the liquid should show no change. 

Alkalies. — To a solution of 5 gm. of ferric ammonium 
sulphate in 100 cc. of water add 15 cc. of ammonia water, 
filter, and evaporate the filtrate. The residue ignited should — 
not exceed 0.002 gm. in weight. 


IRON AND AMMONIUM SULPHATE, FERROUS 


(FERROUS AMMONIUM SULPHATE; Mour’s Sar) 
FeSO.(NH,)2804 + 6H20. Mol. Wt. 392.26. 

Pale, bluish-green crystals, or light, bluish-green crystalline 
powder, soluble in 6 parts of cold water. Ferrous ammonium 
sulphate contains exactly one seventh of its weight of Fe in 
the ferrous condition. 


TESTS OF PURITY 


Ferric Salts. — The solution of 1 gm. of powdered ferrous 
ammonium sulphate in 20 cc. of boiled and cooled water 
(freed from oxygen), with 1 cc. of hydrochloric acid, should 
not afford an immediate red color on adding a few drops of 
potassium sulphocyanate solution. 

Copper, Zinc, and Alkali Salts. — Dissolve 5 gm. of ferrous 
ammonium sulphate in 50 ec. of water, add 5 cc. of nitric 
acid (sp. gr. 1.3), and boil the solution for a few minutes; 
then add to the liquid 15 cc. of ammonia water, let stand for 
about one hour, and filter. The filtrate must be colorless 
(copper). 

Add hydrogen sulphide water to 10 ce. of the filtrate; no 
change in appearance should occur (zinc). 


124 


CHEMICAL REAGENTS 


Evaporate 30 cc. of the filtrate on the water-bath to dryness 
and ignite. No weighable residue should remain. 

Quantitative Determination. — Dissolve 1 gm. of ferrous 
ammonium sulphate in 50 cc. of well-boiled and cooled water, 
add 10 ce. of dilute sulphuric acid, and titrate with decinormal 
potassium permanganate solution. 

1 ec. of decinormal KMnO, = 0.039226 gm. of FeSO, 
(NH,),SO, + 6H,O, log. 59358. 


LACMOID 


(RESORCINOL BLUE) 


Lustrous, dark-violet scales, soluble in alcohol, acetone, 
and ether, and but slightly soluble in water. The solution 
to be used as an indicator is prepared by dissolving 0.5 gm. 
of laemoid in 100 ce. of 95 per cent alcohol, and diluting the 
solution with 100 ec. of water. 


TESTS OF SENSITIVENESS 


(a) Introduce 100 ec. of absolute alcohol into a flask pro- 


vided with a glass stopper, and then add 0.2 ec. of 
the above lacmoid solution; the blue color of the 
alcohol should change to red on the addition of 
0.05 ec. of decinormal hydrochloric acid, and the red 
color should again change to blue on the further 
addition of 0.05 cc. of decinormal potassium hydrox- 
ide. 


(b) Add 0.2 ce. of the above lacmoid solution to 100 ce. of 


distilled water freed from carbon dioxide by pro- 
longed boiling in a platinum dish; the blue color of 
the water must change to red on the addition of 
0.05 ce. of decinormal hydrochloric acid, and the 
red color should again become blue on the further 


CHEMICAL REAGENTS 125 


addition of 0.05 ce. of decinormal potassium hy- 


droxide. 

Notes. — Regarding the use of lacmoid for the titration of alkaloids, 
see C. Kippenberger, Ztschr. anal. Chem., 39, 214 (1900); J. Chem. Soc., 
78, II, 637 (1900). J. Messner, Ztschr. angew. Chem., 16, 444 (1903); 
J. Chem. Soc., 84, II, 519 (1903). 


LEAD ACETATE 
Pb(C2H;02)2 + 3H20. Mol. Wt. 378.99. 


Colorless, translucent crystals, soluble in 2.3 parts of water 
or in 29 parts of 85 per cent alcohol. All the aqueous solu- 
tions for testing should be prepared with well-boiled water, 
to insure freedom from carbon dioxide. 


TESTS OF PURITY 


Earths and Alkalies. — Dissolve 5 gm. of lead acetate in 
about 100 ec. of water, and precipitate the lead from the 
solution with hydrogen sulphide gas; filter, evaporate the 
filtrate, and ignite the residue. The weight of the latter 
should then not exceed 0.001 gm. — 

Copper and Iron. — Dissolve 2 gm. of lead acetate in 40 cc. 
of water, add to the solution 50 cc. of ammonia water and, 
as soon as the precipitate has settled, filter. The precipitate 
must have a pure white color, and the filtrate should be 
colorless. 

Lead Carbonate and Substances Insoluble in Water. — The 
solution of 5 gm. of lead acetate in 50 ec. of water should be 
clear, or only very slightly opalescent. 

Chlorides. — The 1: 30 aqueous solution acidified with nitric 
acid should show no change with silver nitrate solution. 

Nitrates. — The solution of 1 gm. of lead acetate in 30 cc. 
of water, which has been colored a light blue by the addition 
of 1 drop of indigo solution, should not lose its color on 
the addition of 15 cc. of concentrated sulphuric acid. 


126 CHEMICAL REAGENTS 


LEAD CHROMATE 

: PbCrO.. Mol. Wt. 323. 

A yellowish-brown powder, or brown lumps, insoluble in 
water and ammonia water; but almost completely soluble 
in solutions of the fixed alkali hydroxides, and, with decom- 
position, almost wholly soluble also in concentrated nitric 
acid. 


TESTS OF PURITY 


Substances Soluble in Water. — Shake 5 gm. of lead chro- 
mate in fine powder with 50 cc. of warm water (at about 
50°C.) for five minutes, then filter, evaporate the filtrate, and 
ignite the residue. The weight of the latter should not 
exceed 0.001 gm. 

Organic Substances. — Lead chromate should evolve no 
carbon dioxide on ignition. 

Lead chromate which is to be used in the elementary 
analysis of organic compounds should first be gently ignited 
in a current of oxygen, as according to C. H. L. Ritthausen 
[J. prakt. Chem., N. F., 25, 141 (1882); J. Chem. Soc., 42, 
898 (1882)] when ignited in air, it retains carbon, which can 
only be burned off by ignition in a current of oxygen. 


LEAD OXIDE, BROWN 


(LEAD SuperR-, Di-, OR PEROXIDE) 
PbO». Mol. Wt. 238.9. 


i 
LEAD OXIDE BROWN, FREE FROM MANGANESE 


A dark-brown, amorphous powder, insoluble in water. 
The preparation contains 97.5 to 99 per cent of PbO,. 


CHEMICAL REAGENTS 127 


TESTS OF PURITY 


Chlorides. — Boil 5 gm. of lead peroxide with 60 cc. of 
water and 5 ce. of nitric acid, filter, and to 30 cc. of the filtrate 
add silver nitrate solution. At most a slight opalescent 
turbidity should appear. 

Sulphates. — Digest 5 gm. of lead peroxide with 30 cc. of 
a cold saturated aqueous solution of sodium bicarbonate for 
three or four hours, shaking frequently. Then filter, acidulate 
the filtrate with hydrochloric acid, boil the solution for ten 
minutes, and add 2 ec. of barium chloride solution. No 
precipitate -of barium sulphate should form on standing 
twelve hours. 

Substances Soluble in Water (Lead Nitrate, etc.). — Boil 
2 gm. of lead peroxide with 60 cc. of water, and filter; 40 cc. 
of the filtrate should not leave a weighable residue upon 
evaporation and ignition. 

Calcium and Alkalies. — Dissolve 2 gm. of lead peroxide 
in 25 ec. of hydrochloric acid. Dilute the liquid with 200 ce. 
of water, boil ten minutes to expel the chlorine, and super- 
saturate with hydrogen sulphide gas. Filter off the precipi- 
tate, evaporate the filtrate, ignite and weigh the residue. 
The weight should not exceed 0.002 gm. 

Manganese. — Heat 5 gm. of lead peroxide with 10 cc. of 
concentrated sulphuric acid until completely decomposed. 
When cold, mix the mass with 20 ec. of water and add 0.5 
gm. of lead peroxide. On now warming again, the liquid 
should not acquire a red color. 

Quantitative Determination. — Gently heat 1 gm. of lead 
peroxide in a porcelain dish of about 300 ce. capacity with 
30 ce. of nitric acid; then add, while stirring, 30 cc. of semi- 
normal oxalic acid solution, and heat to 60° C. The lead 
peroxide must be completely dissolved by this treatment, 
and the solution should be clear and colorless. Now heat 


128 CHEMICAL REAGENTS 


the solution to the boiling point, and allow semi-normal 
potassium permanganate solution to run into it until the 
red color imparted by 1 drop of the permanganate solution 
no longer completely disappears within half a minute. 13.5 
to 13.7 ec. of the semi-normal potassium permanganate solu- 
tion should be required. 

1 cc. of semi-normal H,C,O, = 0.05973 gm. of PbO,, log. 
77619. 

II 
LEAD OXIDE BROWN, FOR DENNSTEDT’S ULTIMATE 
ANALYSIS 


A dark-brown, amorphous powder, insoluble in water, used 
for ultimate organic analysis according to Dennstedt.* 


TESTS OF PURITY 


Chlorides; Calcium and Alkalies.— The tests are to be 
carried out as detailed under lead peroxide free from man- 
ganese. : 

Sulphates. — Digest 25 gm. of lead peroxide with 50 cc. of 
a cold saturated aqueous solution of sodium bicarbonate for 
three to four hours, shaking frequently. Then filter, acidulate 
the filtrate with hydrochloric acid, boil the solution for ten 
minutes, and add 2 cc. of barium chloride solution. No 
precipitate of barium sulphate should form on standing 
twelve hours. | 

Nitrates. — Boil 1 gm. of lead peroxide with a mixture of 
5 ec. of dilute acetic acid and 10 cc. of water, filter, and 
color the filtrate blue by adding 1 drop of a 1: 1000 indigo 
solution. The blue color should not disappear on the addi- 
tion of 10 ce. of concentrated sulphuric acid. 

* Literature: M. Dennstedt, Ztschr. anal. Chem., 41, 525 (1902); J. 
Chem. Soc., 84, II, 103 (1903); Also: Anleitung zur vereinfachten Ele- 


mentaranalyse, von Prof. Dr. M. Dennstedt, 1903. Published by O. 
Meissner, Hamburg. 


CHEMICAL REAGENTS 129 


Carbonates. — On pouring nitric acid over 5 gm. of lead 
peroxide, no evolution of gas should be seen, even when 
observed through a magnifying glass. 

Quantitative Determination. — This is to be carried out as 
detailed under Lead Peroxide Free From Manganese. 


LEAD OXIDE YELLOW 


(LITHARGE) 
PbO. Mol. Wt. 222.9. 


A yellow or reddish-yellow powder, almost insoluble in 
water (1: 12000), but soluble in nitric acid, acetic acid, and 
potassium hydroxide solution. 


TESTS OF PURITY 


Substances Insoluble in Acetic Acid.— To 2 gm. of lead 
oxide mixed with 5 cc. of water add 10 ce. of dilute acetic 
acid. No evolution of gas should take place. Now boil the 
liquid for several minutes, filter when cold, wash the undis- 
solved residue, dry at 100° C., and weigh. The weight should 
not exceed 0.005 gm. 

Carbonates. — 5 gm. of lead oxide, when heated even to 
the melting-point, should not lose more than 0.005 gm. in 
weight. 

Copper and Alumina. — Dissolve 2 gm. of lead oxide in 
10 cc. of nitric acid and 5 cc. of water with the aid of heat. 
Add to the clear solution 15 cc. of 16 per cent sulphuric acid, 
and filter off the resulting precipitate after it has settled. 
On adding to the filtrate an excess of ammonia water, the 
liquid should not acquire a blue color, nor should a precipitate 
form. 

Nitrates and Nitrites. — Mix 1 gm. of lead oxide with 5 ce. 
of water, and dissolve with the aid of 5 ec. of dilute acetic 
acid. The blue color produced by adding 1 drop of indigo 


130 CHEMICAL REAGENTS 


solution should not disappear on the addition of 10 ce. of 
concentrated sulphuric acid. 

Chlorides. — The solution of 1 gm. of lead oxide in 5 ce. of 
nitric acid diluted with 20 cc. of water should not be affected 
by silver nitrate solution. 

Earths, Gypsum, and Alkalies. are 1 gm. of lead 
oxide in 10 cc. of diluted. acetic acid, add 100 cc. of water, 
and supersaturate with hydrogen sulphide gas. Filter off 
the precipitate, evaporate the filtrate, ignite the residue, and 
weigh. The weight should not exceed 0.003 gm. 


LEAD SUBACETATE SOLUTION 


A clear, colorless, liquid, of specific gravity 1.235 to 1.240. 
Lead subacetate solution is alkaline to litmus paper, but 
does not redden phenolphthalein. 


TEST OF PURITY 


Copper and Iron. — On acidifying 10 cc. of lead subacetate 
solution with 2 cc. of dilute acetic acid, and adding potassium 
ferrocyanide solution, a precipitate forms which should have 
a pure white color. 


LIME, CHLORINATED 


White cubes with chlorine-like odor, and liberating chlorine 
on the addition of hydrochloric acid. 100 parts treated with 
hydrochloric acid should afford at least 25 parts of Cl. 
Specially prepared in cube form for the generation of chlorine 
in the laboratory. 


TEST OF PURITY 


The value of this preparation depends entirely upon its 
active chlorine. 
Quantitative Determination of Active Chlorine. — Mix 0.5 


CHEMICAL REAGENTS 131 


gm. of the powdered cubes with a solution of 3 gm. of potas- 
sium iodide in 60 cc. of water, and add 5 cc. of hydrochloric 
acid. ‘Titrate the liberated iodine with decinormal sodium 
thiosulphate solution, of which at least 35.2 ec. should be 
required. 

1 ce. of decinormal Na,8,0, = 0.003545 gm. of Cl, log. 54962. 


LIME WATER 
(SOLUTION oF CaLcium HypRoxIDE) 


A clear, colorless liquid having a strongly alkaline reaction. 


TEST OF STRENGTH 


Titrate 100 cc. of lime water with normal hydrochloric 
acid, using methyl orange as the indicator. Not less than 
4 cc., nor more than 4.5 cc., of ‘the normal hydrochloric acid — 
should be required to produce the red end-point. 

1 cc. of normal HCl = 0.03705 gm. of Ca(OH),, log. 56879. 


LITMUS 


A specially purified dye obtained from various species of 
lichens. It occurs in the form of friable lumps consisting 
chiefly of erythrolitmin and azolitmin. | 

A large number of formulas have been given for the prep- 
aration of litmus tincture, of which several are described by 
Glaser in his ‘‘ Indikatoren der Azidimetrie und Alkalimetrie.”’ 
A very sensitive litmus tincture may be prepared as follows: 

Dissolve 1 gm. of litmus in 100 ec. of hot water, and add, 
drop by drop, dilute sulphuric acid until the liquid acquires 
a red color. Then boil for ten minutes in order to expel 
completely the carbon dioxide. Should the red color pass 
into blue during the boiling, the color is restored by again 
adding dilute sulphuric acid. Now add baryta water, drop 

by drop, until a violet color develops, set aside to deposit, 


132 _ CHEMICAL REAGENTS 


and filter. Preserve the litmus tincture in bottles not com- 
pletely filled, and simply cover with a loose cap, or stopper 
with a plug of cotton to keep out the dust. 


TEST OF SENSITIVENESS 


Add 0.2 ce. of litmus tincture to 100 ce. of distilled water, 
and boil for some time in a platinum dish to free it from 
carbon dioxide. The violet color of the liquid so obtained 
must change to red on the addition of 0.05 cc. of decinormal 
hydrochloric acid; or must pass into a pure blue color on 
the addition of 0.05 cc. of decinormal potassium hydroxide. 


MAGNESIUM CARBONATE 
MgCOs. Mol. Wt. 84.36. 
White, light pieces, easily reduced to powder; or white, 
bulky powder. Almost insoluble in water, it yet imparts to 
it a slight alkaline reaction. | 


TESTS OF PURITY 


Substances Soluble in Water. — Suspend 5 gm. of powdered 
magnesium carbonate in 50 cc. of water, heat to boiling, and 
filter while hot. Evaporate 20 ce. of the filtrate, and weigh 
the residue, which should not exceed 0.006 gm. 

Substances Insoluble in Hydrochloric Acid.—1 gm. of the 
carbonate should entirely dissolve in 10 cc. of hydrochloric 
acid with 10 ec. of water, and yield a colorless solution. 

Chlorides. — Dissolve 1 gm. of magnesium carbonate in 
5 ec. of nitric acid and 15 ec. of water; on adding silver 
nitrate solution, not more than a slight opalescent turbidity 
should develop. ; . 

Sulphates. — On adding barium ‘chloride solution to the 
solution of 1 gm. of magnesium cabornate in 5 cc. of hydro- 
chlorie acid and 15 ec. of water, no change should occur. 


CHEMICAL REAGENTS 133 


Barium. — The solution of 1 gm. of magnesium carbonate 
in 5 ce. of hydrochloric acid and 15 cc. of water should not 
be rendered turbid on the addition of dilute sulphuric acid. 

Calcium and Alumina. — Dissolve 1 gm. of magnesium 
carbonate in 30 ec. of acetic acid (sp. gr. 1.041) and 30 cc. 
of water. Boil, add 20 cc. of ammonia water and some 
ammonium oxalate solution. The liquid should not become 
turbid within five minutes. 

Heavy Metals. — The solution of 1 gm. of magnesium car- 
bonate in 20 cc. of acetic acid (sp. gr. 1.041) and 30 cc. of 
water should be clear, and should show no change with 
hydrogen sulphide water. 

Iron. — The solution of 1 gm. of magnesium carbonate in 
5 ec. of hydrochloric acid and 15 ec. of water should not 
immediately acquire a blue color on the addition of 0.5 cc. of 
potassium ferrocyanide solution. 


MAGNESIUM CHLORIDE 
MgCl, + 6H.O. Mol. Wt. 203.35. 


White, deliquescent crystals, soluble in about 0.6 part of 
cold, or in 0.3 part of hot, water, and in 5 parts of 85 per 
cent alcohol. The aqueous solution is neutral to litmus 
paper. 

3 TESTS OF PURITY 

Substances Insoluble in Alcohol.—2 gm. of magnesium 
chloride should completely dissolve in 10 cc. of 85 per cent 
alcohol, and yield a clear solution. _ 

_Sulphates. — The solution of 1 gm. of magnesium chloride 
in 20 ce. of water, slightly acidulated with hydrochloric acid, 
should not become turbid on the addition of barium chloride 
solution. 

Phosphates and Arsenates. — Dissolve 3 gm. of magnesium 
chloride and 6 gm. of ammonium chloride in 24 ce. of water, 


134 CHEMICAL REAGENTS 


and add 12 ce. of ammonia water. No turbidity or precipi- 
tate should form on standing twelve hours. 

Ammonium Salts. — On heating 3 gm. of magnesium chlo- 
ride with 10 ec. of sodium hydroxide solution (sp. gr. 1.3), 
no vapors of ammonia should be evolved (to be ascertained 
by moistened litmus paper). 

Barium. — The solution of 1 gm. of magnesium chloride in 
20 cc. of water should afford no reaction on the addition of 
dilute sulphuric acid. 

Heavy Metals and Calcium. 

(a) The solution of 1 gm. of magnesium chloride in 20 ee. 

of water must not be affected by hydrogen sulphide 
water. 

(b) Dissolve 1 gm. of magnesium chloride in 20 ce. of 

water, and add 1 gm. of ammonium chloride and 
5 ec. of ammonia water; no change should occur on 
the further addition of ammonium oxalate solution, 
nor with a few drops of ammonium sulphide solution. 


MAGNESIUM OXIDE 


(MAGNESIA) 
MgO. Mol. Wt. 40.36. 


I 
MAGNESIUM OXIDE 


A white, light, fine powder, almost insoluble in water. 


TESTS OF PURITY 


Substances Soluble in Water. — Heat 0.5 gm. of magnesium 
oxide with 20 cc. of water to boiling, allow to cool, and 
filter off 10 cc. of the supernatant liquid. The filtrate should 
have at most a slight alkaline reaction, and on evaporation 
should not yield a residue weighing more than 0.002 gm. 


CHEMICAL REAGENTS 135 


Substances Insoluble in Hydrochloric Acid.—1 gm. of 
magnesium oxide should completely dissolve in 10 ce. of 
hydrochloric acid and 10 cc. of water, yielding a clear solution. 

Sulphates. — The solution of 0.5 gm. of magnesium oxide 
in 10 cc. of acetic acid (sp. gr. 1.041) should not be imme- 
diately rendered turbid on the addition of barium nitrate 
solution. 

Chlorides. — The solution of 0.5 gm. of magnesium oxide 
in 10 ee. of nitric acid and 10 cc. of water should not be- 
come more than slightly opalescent on the addition of silver 
nitrate solution. 

Carbonates. — Heat 0.5 gm. of magnesium oxide with 10 ce. 
of water, and pour this mixture into 10 cc. of dilute acetic 
acid. Solution should take place without any effervescence; 
only a few individual gas bubbles may occur. 

Barium. — The solution of 1 gm. of magnesium oxide in 
10 ec. of hydrochloric acid and 10 ce. of water should not be 
rendered turbid on the addition of dilute sulphuric acid. 

Calcium. — On shaking 1 gm. of magnesium oxide with 
20 ec. of water and filtering, the filtrate, on the addition of 
ammonium oxalate solution, should not exhibit more than a 
slight opalescence within five minutes. 

Heavy Metals. — The solution of 1 gm. of magnesium oxide 
in 20 ce. of acetic acid (sp. gr. 1.041), should not be affected 
by hydrogen sulphide water. 

Iron. — The solution of 1 gm. of magnesium oxide in 10 ce. 
of hydrochloric acid and 10 cc. of water should not imme- 
diately acquire a blue color on the addition of 0.5 cc. of 
potassium ferrocyanide solution. 


136 CHEMICAL REAGENTS 


IT 
MAGNESIUM OXIDE, FREE FROM SULPHATES 


TESTS OF PURITY 


The tests as given for Magnesium Oxide should be made 
upon this article, and in addition the following one: 

Sulphates. — Dissolve 3 gm. of magnesium oxide in 20 
ec. of hydrochloric acid, dilute the solution to about 100 cc., 
heat to boiling, and add barium chloride solution. No pre- 
cipitate of barium sulphate should form within twelve hours. 


MAGNESIUM SULPHATE 


MgSO; + 7H,0. Mol. Wt. 246.53. 
Clear, colorless, prismatic crystals, only very slightly efflo- 
rescent in air. Soluble in 1 part of cold, and in 0.3 part of 
boiling, water, but insolublein alcohol. The aqueous solution 
is neutral to litmus paper. 


TESTS OF PURITY 


Chlorides. — Dissolve 1 gm. of magnesium sulphate in 
20 ec. of water, and add 1 cc. of nitric acid; the solution 
should not be affected by silver nitrate solution. 

Phosphates, Arsenates, and Heavy Metals. — The tests are 
to be carried out as detailed under Magnesium Chloride. — 

Iron. — 20 cc. of the 1:20 aqueous solution, slightly acidi- 
fied with nitric acid and boiled, should not show a red color 
on the addition of potassium sulphocyanate solution. 

Arsenic. — A mixture of 1 em. of powdered magnesium 
sulphate and 3 ec. of stannous chloride solution should not 
acquire a dark color on standing one hour. 


CHEMICAL REAGENTS 137 


MAGNESIUM AND AMMONIUM CHLORIDE 
MgCl, - NH.Cl + 6H,0. Mol. Wt. 256.87. 
Rhombic crystals, or white crystalline powder, easily 
soluble in water.. Its principal use is in the preparation of 
magnesia mixture for the determination of phosphoric acid. 


TESTS OF PURITY 


Sulphates; Heavy Metals; Calcium and Barium. — The tests 
are to be made as detailed under Magnesium Chloride. 

Phosphates and Arsenates. — Dissolve 5 gm. of magnesium 
and ammonium chloride in 10 cc. of water, and add 5 cc. of 
ammonia water. No turbidity or precipitate should form 
within twelve hours. 


MANGANESE CHLORIDE 


(MANGANOUS CHLORIDE) 
- MnCl, + 4H.20. Mol. Wt. 197.96. 


Reddish, hygroscopic crystals, easily soluble in water 
(about 1:1), and also soluble in alcohol. 


TESTS OF PURITY 


Sulphates. — Dissolve 1 gm. of manganous chloride in 10 cc. 
of water, add 0.25 cc. of hydrochloric acid, and some barium 
chloride solution. No change should be noticeable. 

Chlorine. — The solution of 1 gm. of manganous chloride’ 
in 40 cc. of water and 5 cc. of 16 per cent sulphuric acid 
should not be immediately rendered blue by zinc iodide- 
starch solution. 

Calcium. — 20 cc. of the 1:20 aqueous solution should 
not be immediately rendered turbid on the addition of 2 cc. 
of ammonium oxalate solution.* 


* On allowing this mixture to stand for some time, manganous oxalate 
separates in the form of acicular crystals. 


138 CHEMICAL REAGENTS 


Iron, other Foreign Metals; Salts of Magnesium and the 
Alkalies. — 

(a) Dissolve 1 gm. of manganous chloride in 15 ce. of 
water, add 1 ec. of hydrochloric acid, 3 cc. of chlo- 
rine water, and heat to boiling. The solution, when 
cold, should not acquire a red color on the addition 
of potassium sulphocyanate solution, nor should any 
change appear on the addition of an excess of 
hydrogen sulphide water. 

(b) Precipitate the manganese from a solution of 3 gm. 
of manganous chloride in 50 ce. of water by adding 
ammonium ¢arbonate solution (5 gm. of ammonium 
carbonate in 50 cc. of water). Filter, evaporate 
the filtrate, and ignite the residue. It should not 
weigh more than 0.001 gm. 

Zinc. — Dissolve 1 gm. of manganous chloride and 1 gm. 
of sodium acetate in 10 cc. of water, and add a few drops of 
acetic acid and hydrogen sulphide water. No white precipi- 
tate soluble in hydrochloric acid should form. 


MANGANESE DIOXIDE 


(MANGANESE PrER- OR SUPER-OXIDE; PYROLUSITE) 
MnOs. Mol. Wt. 87.0. 
Grayish-black to steel-blue, brittle, or fibrous pieces pro- 
ducing a black, or grayish-black, streak. The preparation 
contains about 90 per cent of MnQ,. 


TEST OF PURITY 


Quantitative Determination. — Weigh off 1.0875 gm. of 
the manganese dioxide, previously very finely powdered 
and dried to constant weight at 100° C. Place in a flask 
provided with a Bunsen rubber valve, and add 75 cc. (3 pipette- 
fuls of 25 ce. each) of a solution of 100 gm. of pure, crystal- 


CHEMICAL REAGENTS 139 


lized ferrous sulphate and 100 cc. of pure, concentrated 
sulphuric acid in 1000 parts of water.* Close the flask with 
the stopper bearing the Bunsen valve, and heat until the 
manganese dioxide is completely decomposed, leaving no 
dark-colored residue. Then cool, making sure the valve is 
closed as indicated by the collapsing of the rubber tubing. | 
When cold, dilute with 200 cc. of water, and titrate with 
semi-normal potassium permanganate until the faint red color 
no longer disappears, but persists for half a minute (further 
decolorization is neglected). From the quantity of perman- 
ganate corresponding by calculation to the 75 cc. of ferrous 
sulphate solution is now deducted the quantity of per- 
manganate actually used. Each cubic centimeter of the 
difference represents 0.02175 gm., or 2 per cent, of MnO,,. 


MANGANESE SULPHATE 


(MANGANOUS SULPHATE) 
MnSO, + 4H2O. Mol. Wt. 223.12. 


Pale-red, monoclinic crystals, soluble in 0.8 part of water, 
and insoluble in alcohol. The aqueous solution is neutral to 
litmus paper. ; 


TESTS OF PURITY 


Chlorides. — The solution of 1 gm. of manganese sulphate 
in 20 cc. of water should not be rendered more than slightly 
opalescent on the addition of 1 ce. of nitric acid, followed 
by silver nitrate solution. 

Iron, Zinc, and other Foreign Metals; Salts of Magnesium 
and the Alkalies.— The tests are carried out as detailed 
under Manganese Chloride. 

Calcium. — The solution of 1 gm. of manganese sulphate 


* This ferrous sulphate solution is standardized against semi-normal 
potassium permanganate solution on the same day, using the same pipette. 


140 CHEMICAL REAGENTS 


in 20 cc. of water should be perfectly clear, and should afford 
no immediate reaction on the addition of 2 ec. of ammonium 
oxalate solution.* 


MERCURY 
Hg. Atomic Wt. 200. 


A liquid metal with a silvery surface; completely vol- 
atilized by heat, without leaving a residue. 


TESTS OF PURITY 


Foreign Metals. — 

(a) On heating 20 gm. of mercury in a porcelain dish under 
a good draft, no weighable residue should remain. 

(b) On boiling 5 gm. of mercury with 5 cc. of water and 
4.5 gm. of sodium thiosulphate for about one minute, 
in a test-tube, the mercury must not lose its luster, 
and should acquire at most only a slight yellowish 
tinge. 

MERCURY BICHLORIDE 


(MEercurRIC CHLORIDE; CORROSIVE SUBLIMATE) 
HgCl.. Mol. Wt. 270.9. 

White, translucent, prismatic crystals. Mercurie chloride 
is soluble in 16 parts of cold, and in 3 parts of boiling, water; 
in 3 parts of aleohol and in 12 to 14 parts of ether. The 
aqueous solution is acid to litmus paper. 


TESTS OF PURITY 


Foreign Matter not Precipitated by Hydrogen Sulphide. — 
Dissolve 5 gm. of mercuric chloride in 100 cc. of water, add 
5 ec. of hydrochloric acid, and pass into the solution hydrogen 
sulphide gas until the mercury has been completely precipi- 
tated. Then filter, and evaporate the colorless filtrate to 


* See note under Manganese Chloride. 


CHEMICAL REAGENTS 141 


dryness on the water-bath. No weighable residue should 
remain. 

Arsenic. — Shake the mercury sulphide obtained in above 
test with a mixture of 5 cc. of ammonia water and 45 cc. of 
water, filter, and acidulate the filtrate with hydrochloric . 
acid. Neither a yellow color nor a yellow precipitate should 
appear. | ) 

Mercurous Chloride and other Substances Insoluble in 
Ether. — 1 gm. of powdered mercuric chloride should be 
completely soluble in 25 ce. of ether. 


MERCURY NITRATE 
(Mercurous NITRATE) 
HgNO, + H,O. Mol. Wt. 280.05. 

Colorless, monoclinic tables or prisms, soluble in about 2 
parts of warm water, affording a solution with an acid reac- 
tion. On the addition of much water the solution is decom- 
posed with the separation of a light-yellow precipitate. 
Solution is best effected by means of water acidified with 
nitric acid. 

TESTS OF PURITY 

Non-volatile Matter.— On igniting 2 gm. of mercurous 
nitrate, no weighable residue should remain. 

Mercuric Salts. — Dissolve 1 gm. of mercurous nitrate in 
5 ec. of water with 3 to 5 drops of nitric acid. Dilute the 
solution with 15 ce. of water, add an excess of hydrochloric 
acid, filter, and add hydrogen sulphide water to the filtrate. 
More than traces of a precipitate should not be visible. 


MERCURY OXIDE, RED AND YELLOW 


(Mercuric OXIDE) 
HgO. Mol. Wt. 216. 
A heavy, reddish-yellow or yellow powder, easily spiuble 
in dilute hydrochloric or nitric acid, giving a clear solution. 


142 CHEMICAL REAGENTS 


TESTS OF PURITY 


Non-volatile Matter. — On igniting 2 gm. of mercuric oxide, 
no weighable residue should remain. 

_ Chlorides. — The solution of 1 gm. of mercuric oxide in 
5 cc. of nitric acid and 15 cc. of water should not be rendered 
more than slightly opalescent on adding silver nitrate solution. 

Sulphates. — The solution of 1 gm. of mercuric oxide in 
5 ec. of nitric acid and 15 cc. of water should show no change ‘ 
on the addition of barium nitrate solution. 

Nitrates. — Dissolve 1 gm. of mercuric oxide in 2 ce. of 
water and 2 cc. of sulphuric acid, and overlay this mixture 
with 1 cc. of ferrous sulphate solution. No colored zone 
should form even on long standing. 


MERCURY AND POTASSIUM IODIDE 
(Mercuric Potassium JopIDE) 
Hgl.-2KI. Mol. Wt. 785.6. ) 
Sulphur-yellow, crystalline pieces, deliquescent in moist air. 


TEST OF PURITY 


Solubility. —5 gm. of mercuric potassium iodide should 
completely dissolve in 10 cc. of water, and yield a clear 
solution which should remain clear even after adding 80 cc. 
of water. : 


METAPHENYLENEDIAMINE HYDROCHLORIDE 


(METADIAMINOBENZENE HyDROCHLORIDE) 
C.Hu(NH»)2-2HCl. Mol. Wt. 181.06. 
A white, or slightly reddish-white, crystalline powder, easily 
soluble in water. Metaphenylenediamine hydrochloride is 
used as a reagent in the form of a 1: 200 solution. Should 


CHEMICAL REAGENTS 143 


this solution have a color, it is to be decolorized before use 
by heating with previously ignited animal charcoal. 


METHYL ORANGE 


(Soprum SALT OF PARADIMETHYLAMINOAZOBENZENESUL- 
PHONIC ACID) 
(CHs)2:N -CoHy-N:N-CoHs-SOsNa. Mol. Wt. 327.24 
An orange-yellow powder, easily soluble in water. As an 
indicator, a solution of 0.1 gm. in 100 ce. of water is used. 


TEST OF SENSITIVENESS 


To 100 ce. of distilled water in a Jena flask add 1 drop of 
the above methyl orange solution. On adding to this solu- 
tion one drop of decinormal hydrochloric acid, the light- 
yellow color of the water should change to a red, and on 
the further addition of one drop of decinormal potassium 
hydroxide the original color should be restored. 


MIXTURE, KASSNER’S 


This is a mixture of barium dioxide and potassium ferri- 
cyanide, used for generating oxygen. The constituents of 
the mixture are kept stored in separate containers. 


NITROBENZALDEHYDE, ORTHO 
CeH«(NO2)CHO. Mol. Wt. 151.07. 


Light-yellow needles, melting between 45 and 46° C., and 
easily soluble in alcohol and in ether. 


144 CHEMICAL REAGENTS 


NITRON 


FOR THE GRAVIMETRIC DETERMINATION OF 
NITRIC ACID 


(1.4 DipHENYL-3.5 ENDANILODIHYDROTRIAZOL) 
CooHisNs. Mol. Wt. 312.28. 

Shining, yellow leaflets, or amorphous powder, melting at 
189° C. with decomposition. It is soluble in alcohol, chlo- 
roform, acetone, and ethyl acetate, difficultly soluble in ether, 
and insoluble in water. In alcohol,. the substance undergoes 
partial decomposition, indicated by the red color of the 
solution. Nitron is used as a reagent in the form of a 10 
-per cent solution in 5 per cent acetic acid, according to the 
method of M. Busch. 


TEST OF PURITY 


1 gm. of nitron should easily and almost completely dissolve 
in 10 ce. of 5 per cent acetic acid. 


Norn. — Literature: M. Busch, ‘Gravimetrische Bestimmung der 
Salpetersaiire,”’ Ber., 38, 861 (1905); J. Chem. Soc., 88, II, 282 (1905), 
A. Gutbier, Ztschr. angew. Chem., 18, 494 (1905); J. Chem. Soc., 88, II, 
418 (1905). 


NITROPHENOL, ORTHO 
C.6H.OH-NO2. Mol. Wt. 139.08. 
Sulphur-yellow needles or prisms, melting at 44 to 45° C., 
easily soluble in alcohol and in ether, freely soluble in hot 
water, and but slightly soluble in cold water. 


NITROPHENOL, PARA 
CoeH:OH-NO2. Mol. Wt. 139.08. 


Colorless needles or monoclinic prisms, melting at 112° C. 
and easily soluble in alcohol; to some extent also in water. 


CHEMICAL REAGENTS 145 


NITROSOBETANAPHTHOL 
CioHe(NO)(OH). Mol. Wt. 173.10. 


Orange-brown crystals, melting at 109.5° C., insoluble in 
cold water, very difficultly soluble in boiling water, and 
very easily soluble in ether, benzene, and hot alcohol. It is 
used principally for the qualitative and quantitative separa- 
tion of nickel and cobalt. 


PALLADIUM 
Pd. Atomic Wt. 106.5 


Palladium occurs in the form of foil and wire which in 
appearance greatly resemble platinum; also in the form of 
palladium-sponge, a gray spongy mass, and as palladium 
black. The compact metal is soluble in nitrohydrochloric 
acid. Palladium sponge is soluble also in hydrochloric acid 
in the presence of air. 


TESTS OF PURITY 


Differentiation Between Palladium Foil and Platinum Foil. 
—On placing 1 drop of an alcoholic solution of iodine on pal- 
ladium foil, and allowing it to evaporate spontaneously in the 
air, a black spot will be formed on the palladium which will 
disappear on heating the foil to redness. On platinum foil 
similarly treated, no spot is formed. 

Copper and Iron. — Dissolve the palladium in nitrohydro- 
chloric acid, and evaporate the excess of acid on the water- 
bath. Dissolve the residue in water, and add ammonia water 
until the flesh-colored precipitate of ammonium palladous 
chloride first formed redissolves. Then pass into the solu- 
tion gaseous hydrochloric acid, whereby the palladium is 
precipitated as yellow palladosamine chloride, while iron and 
copper remain in solution. The precipitate is filtered off, 


146 CHEMICAL REAGENTS 


and the filtrate treated with ammonia water in excess. No 
coloration or precipitate should ensue. 
Norsr. — Regarding the quantitative determination of palladium, see 


Fresenius, Anleitung zur quantitativen chemischen Analyse, 6 ed., 1, 
348, 481; Fresenius-Cohn, Quantitative Chemical Analysis, 1, 389. 


PALLADIUM CHLORIDE 


(PALLADOUS CHLORIDE) 
PdCl,. Mol. Wt. 177.4. 


Dark-brown, deliquescent mass, easily soluble in water. 
Regarding the quantitative determination see the note under 
Palladium. 

PALLADIUM NITRATE 


(PaLLApous NITRATE) 
Pd(NOs):. . Mol. Wt. 230.58. 


A brown, deliquescent salt, yielding a turbid solution with 
water, due to the almost invariable presence of some basic 
salt. Regarding the quantitative determination, see the note 
under Palladium. 


PALLADIUM AND SODIUM CHLORIDE 


(Soptum PaLLapous CHLORIDE) 
PdCl:-2NaCl. Mol. Wt. 294.4. 


A red, deliquescent salt, soluble in water and in alcohol. 
Regarding the quantitative determination, see the note under 
Palladium. 

PHENACETOLIN 


A brown dye, soluble in alcohol. Phenacetolin is a product 
resulting from the action of concentrated sulphuric acid on 
glacial acetic acid and phenol. The indicator solution is 
prepared by digesting 1 gm. of phenacetolin with warm 
alcohol, then diluting to 100 cc., and filtering. 


CHEMICAL REAGENTS 147 


TEST OF SENSITIVENESS 


Add 2 drops of the indicator solution to 100 ce. of distilled 
water. On the addition of 0.05 cc. of decinormal potassium 
carbonate, the light-brown color of the water should pass — 
into pink; on the further addition of 0.05 cc. of decinormal 
hydrochloric acid, the color should change to a golden yellow. 


PHENOLPHTHALEIN 
CooH 40x. Mol. Wt. 318.11. 


A white or yellowish-white powder, easily soluble in 
alcohol, and melting between 250 and 253° C. Phenolph- 
thalein is used as an indicator in the form of a solution of 
1 gm. in 100 ce. of neutral 95 per cent alcohol. 


TESTS OF PURITY 


Non-volatile Matter. —0.5 gm. of phenolphthalein when 
ignited on platinum foil should yield no weighable residue. 

Solubility in Alcohol. —1 gm. of phenolphthalein should 
give a clear solution with 10 cc. of 95 per cent alcohol. The 
1:100 alcoholic solution should be colorless. 

Sensitiveness. — To 250 cc. of water, which has been well- 
boiled and then cooled, add 3 to 5 drops of phenolphthalein 
solution; the solution should not require more than 0.05 ec. 
of decinormal potassium hydroxide to effect a change from 
colorless to violet (not red). 

_ Fluorane. — 0.5 gm. of phenolphthalein should completely 
dissolve in a mixture of 1 cc. of sodium hydroxide solution 
(sp. gr. 1.168) and 50 cc. of water. 


PHENYLHYDRAZINE 
CeHs -NH.- NH. Mol. Wt. 108.14. 


Colorless or slightly yellowish, highly refractive liquid, 
boiling at 233° C., and solidifying when cold with the for- 


148 CHEMICAL REAGENTS 


mation of-monoclinie plates, melting at 23° C. Phenylhy- 
drazine is but slightly soluble in cold water, but is more 
readily soluble in hot water, and is easily soluble in alcohol 


and in ether. 
TEST OF PURITY 


Solubility. — 2 ec. of phenylhydrazine, when shaken with 
20 cc. of 2 per cent acetic acid, should afford a clear solution. 


PHLOROGLUCIN 
C.H3(OH)3 + 2H.O. Mol. Wt. 162.08. 


A white, or slightly yellowish, crystalline powder, which 
loses its water of crystallization at 100° C., and which, on 
being rapidly heated, melts at 217 to 219° C., but which, 
when slowly heated, melts at a much lower temperature 
(200 to 209° C.). Phloroglucin is easily soluble in water, 
alcohol, and ether. 

TEST OF PURITY 


Diresorcin. — Warm a few milligrams of phloroglucin 
with 1 cc. of concentrated sulphuric acid and 1 to 2 ce. of 
acetic anhydride for five to ten minutes in a boiling water- 
bath. No blue color should develop. 


PLATINUM 
Pt. Atomic Wt. 194.8. 

Platinum occurs in compact form as foil or wire, and in a 
state of very fine subdivision as platinum sponge and plati- 
num black. Compact platinum has a silver-white color; 
platinum sponge is a grayish, spongy mass, while platinum 
black is a black powder. 


TESTS OF PURITY 


Foreign Metals. — Dissolve 1 gm. of the metal in nitro- 
hydrochloric acid, evaporate the solution to dryness on the 


CHEMICAL REAGENTS 149 


water-bath, and convert the residual platinum chloride into 
platinum sponge by strongly igniting. On now treating the 
sponge with nitric acid and filtering, the filtrate should not 
leave more than traces of residue on being evaporated. 
Silver. — Dissolve platinum in nitrohydrochloric acid, evap- 
orate the solution to dryness on the water-bath, and dissolve 
the residue in water. No white residue should remain. 
Norr. — Regarding the further testing of platinum for slight impu- 
rities, see the paper by F. Mylius and P. Foerster: ‘‘Uber die Herstellung 


und Beurteilung von reinem Platin,’’ Ber., 25, 665 (1892); J. Chem. Soc., 
62, 789 (1892). 


PLATINUM CHLORIDE 


(PLATINIC CHLORIDE; CHLORPLATINIC ACID) 
H2PtCle + 6H20. Mol. Wt. 517.61. 
A brownish-red, crystalline, very hygroscopic, saline mass, 
soluble in water, alcohol, and ether, with yellow color. The 
aqueous solution is acid to litmus paper. 


TESTS OF PURITY 


Solubility in Absolute Alcohol. — 1 gm. of platinum chloride 
should dissolve completely in 10 cc. of absolute alcohol, 
yielding a clear solution. Platinic chloride should also afford 
a clear,’ pure yellow solution with water; any red or dark- 
brown tinge would indicate the presence of platinous chloride 
or iridium. | 

Metals Soluble in Nitric Acid. — Strongly ignite 2 gm. of 
platinic chloride. A residue of platinum sponge weighing 
0.752 gm. should be obtained. Digest this residue with 
dilute nitric acid (5 ec. of nitric acid and 20 cc. of water) 
on the water-bath for fifteen minutes, then filter, evaporate 
the filtrate on the water-bath, and ignite the residue so 
obtained. The weight of the latter should not exceed 0.005 


gm. 


150 CHEMICAL REAGENTS 


Sulphates. — The solution of 1 gm. of platinic chloride in 
20 ec. of water should give no precipitate of barium sulphate 
on adding barium chloride solution, and setting aside three 
hours. 

Nitrates. — On mixing 2 cc. of the 1:10 solution with 
2 cc. of concentrated sulphuric acid, and overlaying this 
mixture with 2 cc. of ferrous sulphate solution, no brownish- 
red zone should develop at the contact-surfaces of the two 
liquids, even on long standing. 

Barium Salts.— The 1:20 solution of platinic chloride 
should afford no precipitate of barium sulphate on adding a 
few drops of sulphuric acid, and allowing to stand three 
hours. 


POTASSIUM ACETATE SOLUTION 


A clear, colorless liquid, neutral, or at most slightly acid to 
phenolphthalein; specific gravity 1.176 to 1.18. 100 parts 
contain about 33 parts of potassium acetate. 


TESTS OF PURITY 


Chlorides. — Dilute 5 cc. of potassium acetate solution with 
20 ce. of water, and add 5 ce. of nitric acid followed by silver 
nitrate solution. At most a slight opalescent turbidity 
should develop. 

Sulphates. — Dilute 10 ec. of potassium acetate solution 
with 10 cc. of water, acidify with hydrochloric acid and add 
barium chloride solution. No change should appear. 

Heavy Metals. — 

(a) 15 ce. of potassium acetate solution diluted with 15 ce. 
of water should not become colored on the addition 
of hydrogen sulphide water; nor should a precipitate 
form. . 

(6) On diluting 5 cc. of potassium acetate solution with 
20 ec. of water and adding 1 ec. of hydrochloric 


CHEMICAL REAGENTS 151 


acid, the solution should not acquire a red color 
with potassium sulphocyanate solution. 

Calcium. — Dilute 10 cc. of potassium acetate solution 
with 10 cc. of water, and add ammonium oxalate solution. 
No precipitate of calcium oxalate should form on standing 
three hours. 

POTASSIUM ANTIMONATE 


(Potassium AciID PYROANTIMONATE *) 
K:HSb.207 + 4H.0. Mol. Wt. 504.78. 


A white, granular, crystalline powder, difficultly soluble 
in cold water (1: 250), and more readily soluble in boiling 
water (1:90). 

TESTS OF PURITY 

The aqueous solution of 1 gm. of potassium antimonate in 
100 cc. of boiling water should be neutral to litmus paper. 

On adding 1 gm. of potassium chloride, dissolved in 10 ce. 
of water, to 20 cc. of the 1: 100 aqueous solution, no precipi- 
tate should form within fifteen minutes. | 

To 20 cc. of the 1:100 aqueous solution add 1 gm. of 
ammonium chloride dissolved in 10 ec. of water containing 
2 or 3 drops of ammonia water. No precipitate should form 
within fifteen minutes.t 


POTASSIUM BICARBONATE 
KHCO;. Mol. Wt. 100.15. 


Colorless, transparent, rhombic prisms or plates, soluble in 
4 parts of water. 


* The aqueous solution of potassium antimonate is used as a reagent 
for sodium. It is best to prepare the solution just .before use by boiling 
the salt with water, and filtering. The solutions to be tested for sodium 
should be neutral or slightly alkaline. 

t If a solution of 1 gm. of ammonium chloride in 10 cc. of water is 
added to 20 cc. of the 1: 100 aqueous solution, a voluminous flocculent 
precipitate forms within a few minutes, if the addition of ammonia water 
be omitted. 


152 CHEMICAL REAGENTS 


TESTS OF PURITY 


Sulphates. — On boiling the solution of 3 gm. of potassium 
bicarbonate in 50 ce. of water and 6 cc. of hydrochloric acid 
for several minutes, and then adding barium chloride solution, 
no precipitate of barium sulphate should form within twelve 
hours. 

Chlorides. — Dissolve 3 gm. of potassium bicarbonate in 
50 ec. of water, add 10 cc. of nitric acid and some silver 
nitrate solution. More than a slight opalescence should not 
develop. 

Nitrates. — Dissolve 3 gm. of potassium bicarbonate in 
20 cc. of water and 10 cc. of 16 per cent sulphuric acid; on 
adding to the solution 1 drop of a 1: 1000 indigo solution 
and 10 ec. of concentrated sulphuric acid, the blue color 
should not disappear. 

Silica. — Dissolve 5 gm. of potassium bicarbonate in 20 ce. 
of water and 15 cc. of hydrochloric acid, and evaporate the 
solution on the water-bath in a platinum dish. Dry the 
residue for half an hour at 120° C., and then dissolve it in 
25 ec. of water with 3 ec. of hydrochloric acid. The solution 
‘should be perfectly clear. 

Lime, Alumina, and Heavy Metals. — Dissolve 5 gm. of 
potassium bicarbonate in 25 cc. of water and 15 ce. of diluted 
acetic acid. Add 5 cc. of ammonia water and heat for half 
an hour on the water-bath. No flocks should separate, nor 
should any precipitate form. Furthermore, on adding to 
the slightly alkaline solution some ammonium oxalate solu- 
tion and ammonium sulphide solution, no change should 
appear. 3 

Phosphates. — Dissolve 5 gm. of potassium bicarbonate in 
50 cc. of water, add to the solution 50 ec. of nitric acid, 
25 ec. of ammonium molybdate solution, and heat at 30 
to 40° C. for two hours. No yellow precipitate should form. 


CHEMICAL REAGENTS 153 


Iron. — Dissolve 1 gm. of potassium bicarbonate in 3 cc. 
of hydrochloric acid and 10 ce. of water, add a drop of nitric 
acid and boil, then add potassium sulphocyanate solution. 
No red color should develop. 

Residue on Ignition. — 100 parts of potassium bicarbonate, 
on ignition, should leave 69 parts of residue. 

Quantitative Determination. — On titrating 1 gm. of potas 
sium bicarbonate with normal hydrochloric acid, using methyl 
orange as indicator, 10 cc. of acid should be required. 

1 cc. of normal HCl = 0.10015 gm. of KHCO,, log. 00065. 


POTASSIUM BINIODATE 
KIO;-HIO3. Mol. Wt. 390.09. 


Small, white crystals, clearly and completely soluble in 
20 parts of cold water. 


TESTS OF PURITY 


Quantitative Determination. — The quantitative determina- 
tion may be carried out either acidimetrically or iodometri- 
cally. The salt to be used for the quantitative determination 
must first be brought to constant weight at 98° C. in a 
drying-oven. 

(a) For the acidimetric determination about 3.5 gm. of 

potassium biniodate are dissolved in 200 cc. of water. 

" The titration is made with fifth normal potassium 
hydroxide in the boiling solution, using phenolph- 
thalein as indicator. 

1 cc. of fifth normal KOH = 0.078018 gm. of KIO, * HIO,, 
log. 89218. 

(b) The iodometric determination is made as follows: 

Dissolve 0.10 to 0.15 gm. of potassium biniodate in 
20 cc. of water, add 3 gm. of potassium iodide and 
5 ec. of hydrochloric acid, then dilute the liquid 


154 CHEMICAL REAGENTS 


with 100 cc. of water, and titrate the liberated 
_jiodine with decinormal sodium thiosulphate. 

1cc. of decinormal Na,S,O, = 0.0032507 gm. of KIO, * HIO,, 
log. 51199. 

Potassium biniodate may also be tested as to the correct- 
ness of its composition by coniparing the iodine found in b 
with the quantity of iodine liberated from potassium binio- 
date by potassium iodide without the addition of an acid. 

As will be seen from the equations given below, when 
potassium biniodate is decomposed by potassium iodide, 
without the addition of an acid, it liberates exactly one 
twelfth of the quantity of iodine which is liberated if the 
same quantity of potassium biniodate is decomposed by 
potassium iodide in the presence of hydrochloric or sulphuric 
acid. 

The determination of the quantity of iodine liberated, 
when the decomposition of the biniodate takes place in the 
absence of acid, is carried out as follows: To the solution of 
1 gm. of potassium biniodate in 20 cc. of water, add 3 gm. 
of perfectly neutral potassium iodide. Dilute with 100 cc. of 
water, and titrate the liberated iodine with decinormal 
sodium thiosulphate. It is necessary in carrying out this 
determination to use water perfectly free from carbon dioxide, 
i.e., thoroughly boiled. 

The iodine determined by this method, as well as that 
obtained under 6, and, of course, also the number of cubic 
centimeters required in the titrations, provided the same 
quantities of potassium biniodate are used, bear the ratio 1:12. 

This determination is of special value because the correct 
composition of the preparation may be controlled even — 
without knowing the exact titer of the sodium thiosulphate 
solution. 


Notr.— The course of decomposition of biniodate by potassium 
iodide in the absence of acid may be shown by the following equations: 


CHEMICAL REAGENTS 155 


1. 5KHI.O. + 5KI = 10KIO; + 5HI; 

2. KHI,0O. + 5HI = KIO; + 6I + 3H2O; hence 
3. 6KHI.0, + 5KI = 11KI0O; + 6I + 3H,0. 
One KHI.O., therefore, liberates one I. 


In the presence of an acid, the reaction is as follows: 


KHI.0¢ + 10KI + 11HCl = 11KCl + 6H.O + 121. 
Here, therefore, one KHI.O¢ liberates twelve I. 


POTASSIUM BISULPHATE 


(Potassium Acip SULPHATE) 
KHSO,. Mol. Wt. 136.21. 
Colorless crystals, soluble in 2 parts of water. The aqueous 
solution is acid to litmus paper. 


TESTS OF PURITY 


Heavy Metals. — The solution of 1 gm. of potassium bisul- 
phate in 20 cc. of water should not be affected by hydrogen 
sulphide water; nor by ammonium sulphide solution when 
rendered slightly alkaline with ammonia water. 

Chlorides. — 20 cc. of the 1:20 aqueous solution should 
not be rendered turbid on the addition of silver nitrate 
solution. 

Arsenic. — The mixture of 1 gm. of finely powdered potas- 
slum bisulphate with 3 ec. of stannous chloride solution 
should not acquire a dark color within one hour. 

Quantitative Determination. — Dissolve 1 gm. of potassium 
bisulphate in 50 ce. of water, and titrate with normal potas- 
sium hydroxide, using methyl orange as the indicator. 

1 cc. of normal KOH = 0.13621 gm. of KHSO,, log. 13421. 


POTASSIUM BISULPHITE 
(Potassium Acip SULPHITE) 
KHSOs. Mol. Wt. 120.21. 
A white, crystalline powder, having an odor of sulphurous 
acid and easily soluble in water. The aqueous solution is 
acid to litmus paper. | 


156 CHEMICAL REAGENTS 


TESTS OF PURITY 


Heavy Metals and Arsenic. — Evaporate to dryness on the 
sand-bath a mixture of 5 gm. of potassium bisulphite and 
5 ec. of sulphuric acid (sp. gr. 1.84), and dissolve the residue 
in 20 cc. of water. 10 cc. of this solution should show no 
change on the addition of hydrogen sulphide water. On 
adding to the other 10 cc. of the potassium sulphate solution 
a solution of ammonium molybdate in nitric acid, and heating 
the mixture to 70 to 80° C., the liquid should not acquire a 
yellow color, nor should a yellow precipitate form. ; 

Quantitative Determination. — Dissolve 1 gm. of potassium 
bisulphite in boiled water and dilute to 100 ce. Allow the 
solution to run from a burette into a mixture of 30 cc. of 
decinormal iodine solution and 5 cc. of hydrochloric acid, 
with constant shaking, until decolorization is complete. 

1 cc. of decinormal I = 0.0060105 gm. of KHSO,, log. 77887. 


POTASSIUM BITARTRATE 


(Potassium Acip TARTRATE) 
KHC.H.0¢. Mol. Wt. 188.19. 

A white, crystalline powder, soluble in 192 parts of cold, 
and in 20 parts of boiling, water, and insoluble in alcohol. 
Potassium bitartrate is also soluble in solutions of sodium 
hydroxide and potassium carbonate, with the evolution of 
carbon dioxide. The preparation contains 100 per cent of 
KHC,H,0,. 

TESTS OF PURITY 

Moisture. — 5 gm. of potassium bitartrate, when dried at 
100° C., should not suffer any loss in weight. 

Chlorides. — Dissolve 1 gm. of potassium bitartrate in 20 ec. 
of water and add 5 ec. of nitric acid. The solution must 
not be rendered more than slightly opalescent on the addition 
of silver nitrate solution. 


CH EMICAL REAGENTS 157 


Sulphates. — Dissolve 1 gm. of potassium bitartrate in 
20 ce. of water, add 5.0 cc. of nitric acid and barium nitrate 
solution. No precipitate should form within twelve hours. 

Ammonium Compounds. — On heating 2 gm. of potassium 
bitartrate with 10 cc. of sodium hydroxide solution no vapors 
of ammonia should be evolved (to be ascertained by moist 
litmus paper). 

Calcium. — Dissolve 1 gm. of potassium bitartrate in 5 cc. 
of diluted acetic acid and 25 cc. of water, with the aid of 
heat. Allow to become perfectly cold, filter, and to the 
filtrate add a few drops of ammonium oxalate solution. 
The liquid should show no turbidity within ten minutes. 

Heavy Metals. — The solution of 5 gm. of potassium bitar- 
trate in 25 cc. of water and 25 cc. of ammonia water should 
show no change on the addition of hydrogen sulphide water. 

Quantitative Determination. — 

(a) Dissolve 3.7638 gm. of potassium bitartrate in 200 cc. 
of water, by boiling, and while boiling titrate the 
solution with normal potassium hydroxide, using 
phenolphthalein as the indicator. 20 cc. of the 
potassium hydroxide should be required. 

1 ec. of normal KOH = 0.18819 gm. of KHC,H,O,, log. 

27459. 

(6) Cautiously incinerate 3.7638 gm. of potassium bitar- 
trate in a platinum crucible. When cold, dissolve 
the contents of the crucible in water, and titrate 
cold with normal hydrochloric acid, using methyl 
orange as the indicator. 20 cc. of the hydrochloric 
acid should be required. 

1 ce. of normal HCl = 0.18819 gm. of KHC,H,0,, log. 27459. 


158 CHEMICAL REAGENTS 


POTASSIUM BROMATE 
KBrOs;. Mol. Wt. 167.11. 


Colorless crystals or crystalline powder, soluble in 15 parts 
of cold, or 2 parts of boiling, water. The preparation con- 
tains 100 per cent of KBrQ,. 


TESTS OF PURITY 


Potassium Bromide. — Dissolve 2 gm. of potassium bro- 
mate in 20 cc. of water and add 56 ce. of dilute sulphuric acid. 
The solution should not immediately acquire a yellow color. 

Quantitative Determination. — For this purpose, the salt 
must be dried over sulphuric acid for twenty-four hours. 
Then dissolve 0.10 to 0.15 gm. of the dried potassium bromate 
in 20 cc. of water, add 3 gm. of potassium iodide, 5 cc. of 
hydrochloric acid, and titrate the liberated iodine with 
decinormal sodium thiosulphate. 

1 cc. of decinormal Na.,S8,0, = 0.00278516 gm. of KBrO,, 
log. 44485. 

POTASSIUM BROMIDE 
KBr, Mol. Wt. 119.11. 


White, cubical, lustrous crystals, permanent in the air; 
soluble in 2 parts of water and in about 200 parts of alcohol. 


TESTS OF PURITY 


Potassium Carbonate. — The 1:20 aqueous solution should 
be neutral; it should not render a sensitive red litmus paper 
blue, and should not be reddened on the addition of 1 drop 
of phenolphthalein solution. 

Potassium Bromate. — Potassium bromide which has been 
triturated to powder and spread on a piece of white porcelain 
should not immediately acquire a yellow color on ne a 
few drops of dilute sulphuric acid. 

Heavy Metals, Potassium Sulphate, and Barium Salts. — 


CHEMICAL REAGENTS 159 


20 ec. portions of the 1:20 solution should show no change 
by hydrogen sulphide water nor by barium nitrate solution, 
nor by dilute sulphuric acid. 

Iodides. — Add 2 or 3 drops of ferric chloride solution to 
20 cc. of the 1:20 solution, then add 5 ce. of chloroform and 
shake. The latter should not acquire a violet color. 

Excess of Potassium Chloride.* — On adding a few drops of 
potassium chromate solution to 10 cc. of the aqueous solu- 
tion, prepared from 3 gm. of potassium bromide, dried at 
100° C., and dissolved in 100 ce. of water, the solution should 
not require more than 25.4 cc. of decinormal silver nitrate 
solution to produce a permanent red color. 


POTASSIUM CARBONATE > 
K.CO;3. Mol. Wt. 138.3. 


A white, granular, hygroscopic powder of alkaline reaction, 
soluble in 1 part of water, but insoluble in absolute alcohol. 
The preparation should contain at least 99 per cent of K,CO,. 


TESTS OF PURITY 


Heavy Metals. — 20 cc. of the 1:20 aqueous solution 
should show no change of color on the addition of hydro- 
gen sulphide water. Nor should any change of color be 
shown upon acidulating with hydrochloric acid and then 
adding hydrogen sulphide water. 

Chlorides. — The solution of 1 gm. of potassium carbonate 
in 20 cc. of water, acidified with nitric acid, should afford at 
most a slight opalescence on the addition of silver nitrate 
solution. . ; 

Sulphates. — On acidifying 20 cc. of the 1:20 aqueous 


* Potassium chloride is almost always present in potassium bromide, 
though usually in very small quantities only. The test here given allows 
a maximum of 1 per cent of potassium chloride. 


160 CHEMICAL REAGENTS 


solution with hydrochloric acid, then boiling for a few minutes 
and adding barium chloride solution, no precipitate of barium 
sulphate should form within twelve hours. 

Nitrates. — Dissolve 0.2 gm. of potassium carbonate in 
2 ec. of dilute sulphuric acid, and mix the fluid with 2 cc. of 
concentrated suphuric acid. On now cooling the solution, 
and overlaying it with 1 ec. of a ferrous sulphate solution, 
no reddish-brown zone should form at the contact-surfaces 
of the two liquids. 

Potassium Cyanide. — Dissolve 0.5 gm. of ferrous sulphate 
in 5 ec. of water, add 5 cc. of a 5 per cent potassium carbonate 
solution, and 1 or 2 drops of ferric chloride solution. Heat 
to about 60 to 70° C., and acidulate with hydrochloric acid. 
No green color should develop, nor should a blue precipitate 
form. ‘ 

Sulphides, Sulphites, and Thiosulphates. — On pouring 1 ce. 
of the 1:20 aqueous solution into 10 ec. of decinormal silver 
nitrate solution, a yellowish-white precipitate forms, which 
should not become darker (gray to brownish to black) on 
being heated to 68 to 70° C. 

Phosphoric Acid. — Dissolve 5 gm. of potassium carbonate 
in 50 cc. of water, acidulate the solution with 50 cc. of nitric 
acid, and add 25 cc. of ammonium molybdate solution. No 
yellow precipitate should form on standing two hours at about 
40° C. 

Silica. — Dissolve 5 gm. of potassium carbonate in a plati- 
num dish in 20 ee. of hydrochloric acid and 20 cc. of water, 
and evaporate to dryness. Dry the residue for half an hour 
at 120° C., and then dissolve it in 3 cc. of hydrochloric acid 
and 25 cc. of water. The solution must be perfectly clear. 

Alumina and Calcium. — Dissolve 5 gm. of the carbonate 
in 25 cc. of water and 25 ec. of acetic acid (sp. gr. 1.041), 
add 12 ec. of ammonia water, and heat for half an hour 
on the water-bath. No flocks nor any precipitate should 


CHEMICAL REAGENTS 161 


form, nor should any change take place on the addition of 
ammonium oxalate solution to the slightly alkaline liquid. 

Quantitative Determination. — Dissolve 1 gm. of potassium 
carbonate in 50 ce. of water, add 1 drop of methyl orange 
solution, and titrate with normal hydrochloric acid. At 
least 14.3 cc. of the hydrochloric acid should be required to 
produce the red end-point. 

1 cc. of normal HCl = 0.06915 gm. of K,CO,, log. 83979. 


POTASSIUM CARBONATE SOLUTION 


A clear, colorless, alkaline liquid, of specific gravity 1.330 
to 1.334. 100 parts contain about 33 parts of potassium 
carbonate. 

TESTS’ OF PURITY 

The tests to be made are those given under Potassium 
Carbonate. But use 3 cc. of potassium carbonate solution 
for each gram of potassium carbonate. 


POTASSIUM CHLORATE 
. KCIO3. Mol. Wt. 122.6. 


Colorless, lustrous, tabular crystals, soluble in 16 parts of 
cold, and in 2 parts of boiling, water, and in 130 parts of 
85 per cent alcohol. The salt is practically insoluble in 
absolute alcohol and in ether. The aqueous solution is 
neutral. 

TESTS OF PURITY 

Alkaline Earths; Chlorides. — 20 cc. of the 1:20 aqueous 
solution should be affected neither by ammonium oxalate 
solution nor by silver nitrate solution. 

Heavy Metals. — The solution of 3 gm. of potassium chlo- 
rate in 30 cc. of warm water should be perfectly clear, and 
should remain unchanged on the addition of hydrogen sulphide 
water. 


162 | CHEMICAL REAGENTS | 


Nitrates. — On heating 1 gm. of potassium chlorate with 
5 ec. of sodium hydroxide solution (sp. gr. 1.3), and a mix- 
ture of 0.5 gm. of zine dust and 0.5 gm. of powdered iron, no 
ammonia should be evolved (to be ascertained by moist 
litmus paper). 

Sulphates. — On adding barium chloride solution to 20 ce. 
of the 1:20 aqueous solution, no precipitate of barium. sul- 
phate should form on standing twelve hours. 

Arsenic. — Pour 100 cc. of hydrochloric acid over 20 gm. 
of potassium chlorate in a capacious porcelain dish. As soon 
as the evolution of chlorine has slackened, evaporate the 
solution on the water-bath to dryness. A Marsh apparatus 
is set in operation, containing 20 gm. of arsenic-free, granu- 
lated zinc and dilute (1:5) sulphuric acid. The residue 
from the above evaporation, dissolved in 50 cc. of water, 
is then introducd into the generating flask of the apparatus 
in small portions at a time. No deposit of arsenic should 
be visible in the reduction tube within two hours. 


POTASSIUM CHLORIDE 
KCl. Mol. Wt. 74.6. 


Colorless, cubical crystals, or white, crystalline powder, 
soluble in 3 parts of cold, but more readily soluble in boiling, 
water; insoluble in absolute alcohol or ether. The aqueous 
solution is neutral. | 

TESTS OF PURITY 


Heavy Metals and Alkaline Earths. — The solution of 3 gm. 
of potassium chloride in 50 ec. of water should not be affected 
by ammonium oxalate solution; nor by sodium carbonate 
solution; nor by ammonium sulphide solution. 

Sulphates. — On adding barium chloride solution to 20 ce. 
of the 1:20 aqueous solution, no precipitate of barium sul- 
phate should form on standing twelve hours. 


CHEMICAL REAGENTS 163 


POTASSIUM CHROMATE 


(YELLow PorassitumM CHROMATE) 
K:CrO,. Mol. Wt. 194.4. 
Yellow, rhombic crystals, permanent in the air, soluble in 
2 parts of cold water, but insoluble in alcohol. The 1:20 
aqueous solution is slightly alkaline to litmus paper. 


TESTS OF PURITY 


Free Alkali. — The solution of 0.1 gm. of potassium chro- 
mate in 25 ec. of water should not acquire a red color on 
the addition of a few drops of phenolphthalein solution. 

Sulphates. — Dissolve 3 gm. of potassium chromate in 100 
ec. of water, and add 30 ec. of hydrochloric acid, followed by 
barium chloride solution. No precipitate of barium sulphate 
should form within twelve hours. 

Chlorides. — Dissolve 1 gm. of potassium chromate in 
20 ec. of water, add to the solution 1 ec. of nitric acid, and 
heat the mixture to about 50°C. On now adding a few drops 
of silver nitrate solution, no turbidity or Ba Si should 
form within five minutes. 

Alumina and Alkaline Earths. — Dissolve 2 em. of potas- 
sium chromate in 30 cc. of water, add 5 cc. of ammonium 
oxalate solution, and make slightly alkaline with ammonia 
water. No precipitate should form within twelve hours. 

Quantitative Determination. — Dissolve 1 gm. of potassium 
chromate in water and dilute to 100 ce. Introduce 10 ce. 
of this solution into a glass-stoppered flask of about 400 cc. 
capacity, add 2 gm. of potassium iodide, 5 ec. of 16 per cent 
sulphuric acid, and 350 ec. of thoroughly boiled water. 
Titrate the liberated iodine with decinormal sodium thiosul- 
phate, using starch solution as the indicator. 

1 cc. of decinormal Na,S8,O, = 0.00648 gm. of K,CrQ,, 
log. 81158. 


164 CHEMICAL REAGENTS 


POTASSIUM CYANIDE 
KCN. Mol. Wt. 65.19. 


A white powder, easily soluble in 2 parts of water, and 
readily in boiling 65 per cent alcohol. The aqueous solution 
is alkaline to litmus paper. The salt contains 96 to 98 
per cent of KCN. 

TESTS OF PURITY 


Sulphides. — On adding a solution of lead acetate to the 
solution of 1 gm. of potassium cyanide in 20 cc. of water, 
the resulting precipitate should have a pure white color. 

Carbonates, Sulphocyanates, and Ferrocyanides. — On add- 
ing 5 cc. of hydrochloric acid to the solution of 1 gm. of 
potassium cyanide in 20 cc. of water, — which should be 
done under a hood with a good draft, — only a slight effer- 
vescence should be perceptible. On adding a drop of ferrie 
chloride solution to the acid liquid, neither a red nor a blue 
color should develop. 

-Sulphates.— On adding to 20 ec. of the 1:20 aqueous 
solution 5 ec. of hydrochloric acid, and some barium chloride 
solution, no turbidity should develop. 

Quantitative Determination. — Dissolve 1 gm. of potassium 
cyanide in water and dilute to 100 ce. Dilute 10 ce. of this 
solution with 90 cc. of water, add a granule of sodium chloride, 
and titrate with decinormal silver nitrate solution until a 
permanent, whitish turbidity appears. 

1 cc. of decinormal AgNO, = 0.013038 gm. of KCN, log. 
11521. 


POTASSIUM DICHROMATE 


(Potassium BIcHROMATE) 
K;Cr207. Mol. Wt. 294.5. 
Dark, yellowish-red, triclinic prisms or plates, soluble in 
10 parts of cold, or in about 1.5 parts of boiling, water, and 


CHEMICAL REAGENTS 165 


insoluble in alcohol. The aqueous solution reddens blue 
litmus paper. 


TESTS OF PURITY 


Sulphates. — Dissolve 3 gm. of potassium dichromate in 
100 cc. of water, and add 30 ec. of hydrochloric acid followed 
by barium chloride solution. No precipitate of barium sul- 
phate should form on standing twelve hours. 

Chlorides. — Dissolve 1 gm. of potassium dichromate in 
20 ec. of water, add 10 ce. of nitric acid, and heat the mix- 
ture to about 50° C. On now adding a few drops of silver 
nitrate solution, no turbidity should develop nor should a 
precipitate form, within five minutes. | 

Alumina and Alkaline Earths. Add ammonium oxalate 
solution to 2 gm. of potassium dichromate dissolved in 30 ce. 
of water, and make slightly alkaline with ammonia water. 
No precipitate should form within twelve hours. 

Quantitative Determination. — Dissolve 1 gm. of potassium 
dichromate in water, dilute to 100 cc., and introduce 10 ce. 
of this solution into a glass-stoppered flask of about 400 cc. 
capacity, together with 2 gm. of potassium iodide and 5 
ce. of 16 per cent sulphuric acid. Dilute with 350 ce. of 
thoroughly boiled water, and titrate the liberated iodine with 
decinormal sodium thiosulphate, using starch solution as the 
indicator. 

1 ec. of decinormal Na.S,O, = 0.0049083 gm. of K,Cr,0,, 
log. 69092. 


POTASSIUM FERRICYANIDE 


(Rep PrussiaTE OF PoTasH) 
-K3Fe (CN)s. Mol. Wt. 329.59. 


Ruby-red, shining crystals, soluble in 2.5 parts of cold, 
and in 1.5 parts of boiling, water. 


166 CHEMICAL REAGENTS 


TESTS OF PURITY 


Ferrous Salt. — On first removing the superficial layers of 
a crystal by washing with water, and then preparing a 3 
per cent aqueous solution from the washed crystals, the 
solution must not acquire a blue color on the addition of a 
few drops of a dilute ferric chloride solution. 

Sulphates. — On adding 1 cc. of hydrochloric acid to 20 ce. 
of the 1:20 aqueous solution, and then adding barium 
chloride solution, no precipitate of barium sulphate should 
form on standing twelve hours. 

Chlorides. — Deflagrate a mixture of 0.5 gm. of powdered 
potassium ferricyanide and 1 gm. of potassium nitrate* by 
introducing small quantities at a time into a porcelain cru- 
cible heated to redness. Fuse for a few minutes over the 
free flame, and after the melt has cooled add 20 ce. of water. 
Filter, to the filtrate add 0.5 gm. of potassium nitrate, evap- 
orate to dryness, refuse in a porcelain crucible until quiescent, 
and allow to cool. When cold, dissolve in 20 cc. of water, 
add 3 cc. of nitric acid and silver nitrate solution. The 
liquid should show at most a slight opalescence. 


Norts. — Regarding the quantitative determination of potassium ferri- 
cyanide, see Mohr’s Lehrb. Chem.-anal. Titriermeth., 7 ed., p. 249; Sutton, 
Volumet. Anal., 9 ed., p. 210. 


POTASSIUM FERROCYANIDE 


(YELLOW PRUSSIATE OF POTASH) 

K,Fe (CN). + 3H20. Mol. Wt. 422.78. 

Citron-yellow, tabular crystals, which are quite permanent 

in the air and are soluble in 4 parts of cold, and 2 parts of 
boiling, water; insoluble in alcohol. 


* The potassium nitrate should be tested for chloride and perchlorate. 
See under Potassium Nitrate. 


CHEMICAL REAGENTS 167 


TESTS OF PURITY 


Carbonates. — On treating 1 gm. of powdered potassium 
ferrocyanide with dilute sulphuric acid, there should be no 
evolution of gas. » : 

Sulphates. — Dissolve 1 gm. of potassium ferrocyanide in 
20 cc. of water, and add 1 cc. of hydrochloric acid followed 
by barium chloride solution. No immediate turbidity should 
ensue. 

Chlorides. — Deflagrate a mixture of 0.5 gm. of powdered 
potassium ferrocyanide and 1 gm. of potassium nitrate,* by 
introducing small quantities at a time into a porcelain cru- 
cible heated to redness. Treat the residue with 20 ce. of 
water, filter, and to the filtrate add 3 cc. of nitric acid and 
silver nitrate solution. The liquid should not develop more 
than a slight opalescence. 


Norr. — Regarding the quantitative determination of potassium ferro- 
cyanide, see Mohr’s Lehrb. Chem.-anal. Titriermeth., 7 ed., p. 245; Sutton, 
Volumet. Anal., 9 ed., p. 209. 


POTASSIUM HYDROXIDE 


(Caustic PorasH; Potasstum HypRATE) 
KOH. Mol. Wt. 56.15. | 


In the laboratory, three grades of potassium hydroxide 
are generally used: 

1. Potassium Hydroxide, Purest. 

2. Potassium Hydroxide, Purified by Alcohol. 

3. Potassium Hydroxide, Purified. 

These three preparations differ chiefly in thew content of 
chloride, sulphate, silica, and alumina. 


* The potassium nitrate should be tested for chloride and perchlorate. 
See under Potassium Nitrate. 


168 CHEMICAL REAGENTS 


I 
POTASSIUM HYDROXIDE, PUREST 


White pieces showing a crystalline structure on fracture. 
The preparation contains 82 to 85 per cent of KOH. 


TESTS OF PURITY 


Sulphates. — Dissolve 3 gm. of potassium hydroxide in 
50 ec. of water, add 10 cc. of hydrochloric acid, heat to 
boiling, and then add barium chloride solution. No precipi- 
tate of barium sulphate should form on standing twelve hours. 

Chlorides. — Dissolve 1 gm. of potassium hydroxide in 
20 ce. of water, and add 5 cc. of nitric acid, followed by a 
few drops of silver nitrate solution. Not more than a slight 
opalescent turbidity should develop within one minute. 

Nitrates. — 

(a) Dissolve 2 gm. of potassium hydroxide in 10 ee. of 

water, add 10 ec. of 16 per cent sulphuric acid, 
1 drop of 1: 1000 indigo solution, a granule of sodium 
chloride, and 10 ec. of concentrated sulphuric acid. 
The blue color of the mixture should not disappear 
within ten minutes. 

(b) Dissolve 25 gm. of potassium hydroxide in 100 cc. of 

water in a distillation flask. To the solution add 
5 gm. of zine dust and 5 gm. of powdered iron by 
hydrogen. Connect the flask with a condenser and 
a U-tube receiver containing 3 to 5 ce. of fifth nor- 
mal hydrochloric acid and 10 cc. of water; allow to 
stand for a few hours, and then distil off about 25 cc. 
over a small flame. Titrate the distillate with fifth 
normal potassium hydroxide, using methyl orange 
as the indicator. At most 0.2 cc. of fifth normal 
hydrochloric acid should have been required to neu- 
tralize the ammonia. 


CHEMICAL REAGENTS 169 


Phosphoric Acid. — Dissolve 5 gm. of potassium hydroxide 
in 50 ec. of water and add 50 ce. of nitric acid, followed by 
25 ec. of a solution of ammonium molybdate in nitric acid. 
This mixture should deposit no yellow precipitate on standing 
two hours at about 40° C. 

Silica. — Dissolve 5 gm. of potassium hydroxide in 25 ce. 
of water in a platinum dish, add 25 cc. of hydrochloric acid, 
and then evaporate to dryness on the water-bath. Dry the 
residue for half an hour on the sand-bath at about 120° C., 
and. then dissolve it in 10 ce. of hydrochloric acid and 90 ce. 
of water. Any insoluble residue should be filtered off, 
washed, and ignited. Its weight should not exceed 0.0005 gm. 

Alumina, Calcium, and Heavy Metals. — 5 gm. of potassium 
hydroxide should yield a clear and colorless solution with 
10 cc. of water. To this solution add 25 cc. of acetic acid 
(sp. gr. 1.041), followed by 10 cc. of ammonia water, dilute 
with 65 cc. of water, and heat the fluid on the water-bath 
until the odor of ammonia has entirely disappeared. Now 
add 2 or 3 drops of ammonia water, and allow to stand 
twelve hours. At the end of this time there should be no 
precipitate, or, at most, only an exceedingly slight, flocculent 
precipitate. In the latter case the precipitate is collected 
by filtration, washed, and ignited. Its weight should not 
exceed 0.0005 gm. The following tests are now carried out 
with the filtrate: 

To 50 cc. add a few cubic centimeters of ammonium oxalate 
solution. No precipitate of calcium oxalate should form 
within two hours. 

To 50 ec. add a few drops of ammonium sulphide solution. 
No change should appear. 

Substances Insoluble in Alcohol (Potassium Carbonate and 
Other Potassium Salts). —5 gm. of potassium hydroxide 
should completely dissolve in 25 cc. of 85 per cent alcohol 
on warming, giving a perfectly clear and colorless solution. 


170 CHEMICAL REAGENTS 


Quantitative Determination, and Determination of the 
Potassium Carbonate Content. — Titrate a cold solution of 
1 gm. of potassium hydroxide in 100 ec. of water with normal 
hydrochloric acid, using phenolphthalein as the indicator. 
At least 14.8 ec. of the acid should be necessary to destroy 
the red color. (First titration.) Now add 1 drop of methyl 
orange, and titrate further until the color again changes to 
red. In this second titration, not more than 0.15 ec. of the 
acid should be required (2.07 per cent K,CO,).* 

le. of normal HCl = 0.05615 gm. of KOH, log. 74935. 

1 cc. of normal HCl = 0.06915 gm. of K,CO,, log, 83979. 


II 
POTASSIUM HYDROXIDE, PURIFIED BY ALCOHOL 


White, very hygroscopic sticks or pieces, exhibiting a 
crystalline fracture. The preparation contains at least 80 
per cent of KOH. . 
TESTS OF PURITY 

Sulphates and Nitrates. — The test is carried out as detailed 
under Potassium Hydroxide, Purest. 

Chlorides. — Dissolve 1 gm. of potassium hydroxide in 
20 cc. of water, add 5 cc. of nitric acid and a few drops of 
silver nitrate solution. An opalescence may develop, but no 
precipitate should form. 

Silica. — Dissolve 5 gm. of potassium hydroxide in 25 ee. 
of water and 25 cc. of hydrochloric acid in a platinum dish, 

* From the results of both titrations, the content of potassium hydroxide 
and potassium carbonate are calculated as follows: 

The result of the second titration multiplied by two gives the number 


of cubic centimeters which are necessary to neutralize the potassium 


carbonate originally present. 

On subtracting the number of cubic centimeters required in the second 
titration from the number of cubic centimeters used in the first titration, 
the remainder gives the number of cubic centimeters which were required 
to neutralize the potassium hydroxide. 


CHEMICAL REAGENTS Biya 


and evaporate to dryness on the water-bath. Dry the residue 
for half an hour on the sand-bath at about 120° C., then 
treat it with 10 cc. of hydrochloric acid and 90 cc. of water, 
filter, wash, and ignite any undissolved residue. The weight 
of the latter should not exceed 0.0025 gm. 

Alumina, Calcium, and Heavy Metals. — 5 gm. of potassium 
hydroxide should completely dissolve in 20 cc. of water, 
affording a clear and colorless solution. Dilute the solution 
to 100 ec., and add 25 ce. of acetic acid (sp. gr. 1.041) followed 
by 10 ec. of ammonia water. At most a slight turbidity, but 
no flocculent precipitate of aluminum hydroxide should de- 
velop within five minutes; and no immediate change should 
appear on the addition of ammonium oxalate and ammonium 
sulphide solutions. : 

Quantitative Determination and Determination of the 
Potassium Carbonate Content. — Dissolve 1 gm. of potassium 
hydroxide in 100 cc. of water, and titrate the cold solution 
with normal hydrochloric acid, using phenolphthalein as the 
indicator. At least 14.5 ec. of the acid should be necessary 
to destroy the red color. Now add 1 drop of methyl orange, 
and titrate further until the color again changes to red. In 
this second titration not more than 0.25 ce. of the acid should 
be required (3.45 per cent K,CO,).* 


Ill 
POTASSIUM HYDROXIDE, PURIFIED 


White, very hygroscopic sticks or pieces which exhibit a 
crystalline fracture. The preparation should contain at 
least 80 per cent of KOH. 

TESTS OF PURITY 

Nitrates. — Dissolve 2 gm. of potassium hydroxide in 10 ce. 

of water, and add 10 ce. of dilute sulphuric acid, followed by 


* See the note under Potassium Hydroxide, Purest. 


172 CHEMICAL REAGENTS 


1 drop of 1:1000 indigo solution, a granule of sodium chlo- 
ride, and 10 cc. of concentrated sulphuric acid. The blue 
color of the mixture should not disappear within ten minutes. 

Alumina, Calcium, and Heavy Metals. — 2.5 gm. of potas- 
sium. hydroxide should completely dissolve in 10 ce. of water 
yielding a clear and colorless solution. Dilute the solution to 
100 cc. and add 15 ce. of acetic acid (sp. gr. 1.041), followed 
by 10 cc. of ammonia water; a slight turbidity may form 
within five minutes, but no flocculent precipitate of alumi- 
num hydroxide should develop.. The solution so tested, 
filtered if necessary, should not exhibit an immediate tur- 
bidity on adding ammonium oxalate solution; and on ‘the 
addition of ammonium sulphide solution should acquire at 
most a slight green color. , | 

Quantitative Determination and Determination of the Po- 
tassium Carbonate Content. — The determinations are made 
as detailed under Potassium Hydroxide, Purified by Alcohol. 
The content of potassium carbonate should not exceed 5 per 
cent. 


POTASSIUM HYDROXIDE SOLUTIONS 


A clear, colorless liquid, of specific gravity 1.3, and con- 
taining about 32 per cent of potassium hydroxide. 

Also a similar solution having a specific grayity 1.138 to 
1.140 and containing about 15 per cent of potassium 
hydroxide. 


TESTS OF PURITY 


The tests and the quantitative determination, as given 
under Potassium Hydroxide, Purified by Alcohol, are to be 
made on each solution. But, of the solution having sp. gr. 
1.3, use 2 ec. (2.6 gm.) in place of each gram of the solid 
hydroxide referred to. And, of the solution having sp. gr. 
1.138 to 1.140, use 5 cc. (5.7 gm.). 


CHEMICAL REAGENTS 173 


POTASSIUM IODATE 
KIO;3. Mol. Wt. 214.12. 


A white, crystalline powder, soluble in 13 parts of cold, 
and in 3 parts of boiling, water. The aqueous solution 
should be clear and have no acid reaction. The preparation 
contains 100 per cent of KIO,. 


TESTS OF PURITY 


Free Acid. — Dissolve about 0.5 gm. of potassium iodate 
in about 20 cc. of boiled water, and add a small crystal of 
neutral potassium iodide and a few drops of freshly prepared 
starch solution. The liquid should not immediately acquire - 
a blue color. 7 . 

Iodides. — Dissolve 2 gm. of potassium iodate in 20 cc. of 
water, add 5 cc. of dilute sulphuric acid and a few drops of 
starch solution. The liquid should not immediately acquire 
a blue color. 

Quantitative Determination. — Previous to the quantita- 
tive determination, the salt should be dried for twenty-four 
hours over sulphuric acid. 

Dissolve 0.10 to 0.15 gm. of dried potassium iodate in 
20 cc. of water, add 3 gm. of potassium iodide and 5 ce. of 
hydrochloric acid. Dilute with 50 cc. of water, and titrate 
the liberated iodine with decinormal sodium thiosulphate. 

1 ec. of decinormal Na,S,0O, = 0.0035686 gm. of KIO,, 
log. 55250. 


POTASSIUM IODIDE 
KI. Mol. Wt. 166.12. 

White, cubical crystals, not becoming moist on contact 
with air. Potassium iodide is soluble in about 0.75 part of 
water, in about 12 parts of 85 per cent alcohol, and in 40 
parts of absolute alcohol. 


174 | CHEMICAL REAGENTS 


TESTS OF PURITY 


Potassium Carbonate. — Potassium iodide when crushed 
and placed upon moistened red litmus paper should not 
immediately color the latter violet-blue. 

On adding to a solution of 0.5 gm. of potassium iodide in 
10 ec. of water 1 drop of phenolphthalein solution, no red 
color should develop. 

Metals and Sulphates. — 20 cc. portions of the 1: 20 aqueous 
solution should afford no reaction with either hydrogen 
sulphide water or barium chloride solution. 

Cyanides. — On adding to 20 cc. of the 1:20 aqueous 
solution a granule of ferrous sulphate, 1 drop of ferric chloride 
solution, and 5 ce. of sodium hydroxide solution (sp. gr. 1.3), 
then heating the mixture to 50 to 60° C., and adding 10 ce. 
of hydrochloric acid, no blue color should develop. 

Iodates. — 20 cc. of the 1:20 solution, freshly prepared 
with recently boiled and cooled water, should not immediately 
acquire a blue color on the addition of starch solution and 
2 to 3 drops of dilute sulphuric acid. 

Nitrates. — On heating 1 gm. of potassium iodide with 
5 ec. of sodium hydroxide solution and a mixture of 0.5 gm. 
of zinc dust and 0.5 gm. of powdered iron, no vapors of 
ammonia should be evolved (to be ascertained by moist litmus 
paper). 

Chlorides, Bromides, and Thiosulphates. — Dissolve 0.2 gm. 
of potassium iodide in 2 cc. of ammonia water, add 13 ce. of 
decinormal silver nitrate solution, shake, and filter. On 
supersaturating the filtrate with nitric acid, the solution 
should not become so cloudy as to be opaque nor should a 
dark color develop, within ten minutes. 


CHEMICAL REAGENTS : 175 


POTASSIUM IODIDE, NEUTRAL 
TESTS OF PURITY 


Neutrality. — Dissolve 10 gm. of the neutral potassium 
iodide in 50 cc. of water, in a stoppered, flint-glass bottle, 
overlay with 30 cc. of ether, and add 3 drops of iodeosin 
solution. After vigorously shaking, the aqueous layer will 
exhibit a pale-red color which disappears on adding 1 drop 
of decinormal hydrochloric acid and thoroughly shaking. 

Should the water which has been used for making the 
solution of potassium iodide have an alkaline reaction to 
iodeosin, it must be first rendered neutral to it. 

Further Tests. — The tests as given under Potassium Iodide 
are also to be made, and in the manner there described. 


POTASSIUM NITRATE 
KNOs. Mol. Wt. 101.19. 


Colorless, transparent, prismatic crystals, or crystalline 
powder, permanent in air, and soluble in 4 parts of cold, 
and in less than 0.5 part of boiling, water; almost insoluble 
in alcohol. The aqueous solution is neutral to litmus paper. 


TESTS OF PURITY 


Sulphates. — Dissolve 3 gm. of potassium nitrate in 60 cc. 
of water, and add 0.5 cc. of hydrochloric acid followed by 
barium chloride solution. No precipitate of barium sulphate 
should form on standing twelve hours. 

Chlorides. — Dissolve 1 gm. of potassium nitrate in 20 ce. 
of water, acidulate with 1 cc. of nitric acid and add silver 
nitrate solution. No turbidity should develop. 

Chlorates and Perchlorates. — Gently ignite 1 gm. of po- 
tassium nitrate, dissolve the melt in 20 cc. of water, add 
1 cc. of nitric acid and some silver nitrate solution. No 
change should appear. 


176 CHEMICAL REAGENTS 


Calcium and Heavy Metals. — 

(a) The solution of 3 gm. of potassium nitrate in 50 cc. 
of water should not be affected by hydrogen sulphide 
water. 

(b) The solution of 3 gm. of potassium nitrate in 50 ce. 
of water should not be affected by ammonia water; 
nor by the further addition of ammonium oxalate 
solution and of ammonium sulphide solution. 

Iron. — 20 ec. of the 1:20 aqueous solution, acidulated 
with 1 ec. of hydrochloric acid (sp. gr. 1.124), should not be 
reddened by potassium sulphocyanate solution. 

Nitrites. — Dissolve 1 gm. of potassium nitrate in 20 cc. 
of water, acidulate with 1 cc. of 16 per cent sulphuric acid, 
and add 1 ce. of a freshly prepared, colorless 1: 200 solution 
of metaphenylenediamine hydrochloride.* No yellow or 
yellowish-brown color should develop. 


POTASSIUM NITRITE 
KNOs. Mol. Wt. 85.19. 


White, or slightly yellowish, tough sticks, which are del- 
iquescent in the air, and are easily soluble in water. The 
aqueous solution is alkaline to litmus paper. The prepara- 
tion contains at least 90 per cent of KNO,,. 


TESTS OF PURITY 


Heavy Metals. —On adding a few drops of ammonium 
sulphide solution to 20 cc. of the 1:20 aqueous scteoue no 
change should appear. 

Sulphates. — On adding to 20 cc. of the 1:20 aqueous 
solution 5 ce. of nitric acid and barium nitrate solution, no 
turbidity should develop. 

* Should the solution of metaphenylenediamine hydrochloride have a 


color, it is to be decolorized before using by iki with previously 
ignited animal charcoal. 


CHEMICAL REAGENTS 177 


Quantitative Determination. — Dissolve 10 gm. of potas- 
sium nitrite in water and dilute to 1000 cc. Make a mixture 
of 50 cc. of decinormal potassium permanganate (accurately 
measured) with 300 cc. of water and 25 cc. of 16 per cent 
sulphuric acid,. warm to 40 to 50° C, and, while constantly 
shaking, allow the nitrite solution to run slowly into it, until 
the red color disappears. Care must be taken towards the 
end to run in the nitrite solution very slowly, because the 
change from red to colorless requires some time. Not more 
than 23.7 cc. of the potassium nitrite solution should be 
required. 

1 ec. of decinormal KMnO, = 0.0042595 gm. of KNO,, 
log. 62936. 


POTASSIUM OXALATE, NEUTRAL 
K:C204 H.0. Mol. Wt. 184.308. 


Rhombic prisms, soluble in 3 parts of water. The aqueous 
solution is neutral to litmus paper. 


TESTS OF PURITY 


Sulphates. — Boil a solution of 5 gm. of potassium oxalate 
in 200 cc. of water, and add 5 ee. of hydrochloric acid followed 
by barium chloride solution. No precipitate of barium sul- 
phate should form on standing twelve hours. 

Chlorides. — Dissolve 1 gm. of potassium oxalate in 25 ce. 
of water, and add 10 ce. of nitric acid and a few drops of 
silver nitrate solution. No turbidity should develop on 
shaking. 

Heavy Metals. — To a solution of 1 gm. of potassium oxalate 
in 25 ec. of water, add hydrogen sulphide water. The solu- 
tion should remain unchanged. On now adding to the liquid 
5 cc. of ammonia water, no green color should develop, nor 
should a precipitate form. 


178 CHEMICAL REAGENTS 


Quantitative Determination. — Dissolve about 3.2 gm. of 
potassium oxalate in water and dilute to 500 cc. To 50 cc. 
of this solution add 6 to 8 cc. of concentrated sulphuric acid, 
heat the liquid to about 60° C., and titrate with decinormal 
potassium permanganate. 

1 ec. of decinormal KMnO, = 0.0092158 gm. of K,C,O, + 
H,0, log. 96453. 


POTASSIUM PERCHLORATE 
KClO,. Mol. Wt. 138.6. 


Colorless, rhombic prisms, soluble in about 65 parts of 
cold, and in 8 parts of boiling, water, and insoluble in 
alcohol.* 


TESTS OF PURITY 


Calcium; Chlorides. — 20 cc. of the 1:20 aqueous solution 
prepared by the aid of heat should not be affected by am- 
monium oxalate solution; and it should develop at most a 
slight opalescence on the addition of silver nitrate solution. 

Heavy Metals. — 20 cc. of the 1:20 aqueous solution pre- 
pared with the aid of heat should not be affected by hydrogen 
sulphide water. 

Nitrates. — On heating a mixture of 1 gm. of potassium 
perchlorate with 5 cc. of sodium hydroxide solution (sp. gr. 
1.3) and a mixture of 0.5 gm. of zine dust and 0.5 gm. of 
powdered iron, no vapors of ammonia should be evolved 
(to be ascertained by moist litmus paper). 

Sulphates. — On adding barium chloride solution to 20 ec. 
of the 1:20 aqueous solution prepared by the aid of heat, 
no change should appear. 


* Potassium perchlorate is distinguished from potassium chlorate by 
the fact that it dissolves without color in concentrated sulphuric acid, 
and is not decomposed by hydrochloric acid with the liberation of free 
chlorine. 


CHEMICAL REAGENTS 179 


POTASSIUM PERMANGANATE 
KMn0O,. - Mol. Wt. 158.15. 


I 
POTASSIUM PERMANGANATE 


Dark-violet, almost black prisms, exhibiting a steel-blue 
luster, soluble in 16 parts of cold, and in 8 parts of boiling, 
water. The 1:1000 aqueous solution is neutral to litmus 


paper. 


TESTS OF PURITY 


Sulphates and Chlorides. — Boil 0.5 gm. of potassium per- 
manganate. with a mixture of 2 ec. of 95 per cent alcohol 
and 25 cc. of water, and filter. The filtrate should be color- 
less, and, after adding to it 2 cc. of nitric acid, barium nitrate, 
and, silver nitrate solutions, it should not develop more than 
a slight opalescence. 

‘Nitrates. — Add gradually 1 gm. of crystallized oxalic acid 
to a solution of 0.5 gm. of potassium permanganate in 5 cc. 
of water, heat to 50 to 60° C., and filter. On overlaying 
1 cc. of ferrous sulphate solution on a mixture of 2 cc. of the 
_clear colorless filtrate and 2 cc. of concentrated sulphuric 
acid, no dark-colored zone should form at the contact-surfaces 
of the two liquids. 

Chlorates. — Heat 2 gm. of potassium permanganate in a 
platinum crucible, and gradually add small pieces of paraffin 
until no more glowing is observed. When cold, the residue 
is treated with 20 cc. of water, filtered, and 5 cc. of nitric acid 
and silver nitrate solution are added to the filtrate. The 
liquid should develop at most a slight opalescence. 

Quantitative Determination. — Dissolve 3.164 gm. of po- 
tassium permanganate in water and dilute to 1000 cc. Also 


180 CHEMICAL REAGENTS 


dissolve 6.715 gm. of sodium oxalate,* dried at 240° C. (see 
Sodium Oxalate, Sdrensen’s), in water and dilute to 1 liter 
(decinormal sodium oxalate). Measure off 30 cc. of the 
oxalate solution with a burette, add to it 6 to 8 ec. of concen- 
trated sulphuric acid, heat to about 60° C. ,and run in the 
potassium permanganate solution until a permanent red color 
appears. | 

1 ec. of decinormal Na.C,0, = 0.003164 gm. of KMnQ,, 
log. 50024. 

II 


POTASSIUM PERMANGANATE, FREE FROM 
SULPHATES 


The preparation contains 99.7 to 100 per cent of KMn0O,. 


TESTS OF PURITY 


Sulphates. — The solution of 3 gm. of potassium perman- 
ganate in 150 cc. of water with 15 cc. of 95 per cent alcohol 
(or a little hydrogen peroxide, 30 per cent), heated, if neces- 
sary, until perfectly decolorized, should yield a filtrate which, 
on the addition of 2 ec. of hydrochloric acid and barium 
chloride solution, should afford no precipitate of barium 
sulphate on standing twelve hours. 

Further Tests.— The other tests and the quantitative 
determination as given under Potassium Permanganate are‘ 
also to be made. 


POTASSIUM STANNOSULPHATE 
(MariaNnac’s SALT) 
KSn(SO.)o. Mol. Wt. 389.42. 
White crystals, soluble in dilute potassium or sodium 
hydroxide solution, and in hydrochloric acid. 


* The proper composition of the sodium oxalate is verified and con- 
trolled by qualitative tests and by titration with fifth normal hydrochloric 
acid. 


CHEMICAL REAGENTS 181. 


TEST OF PURITY 


Quantitative Determination. — Dissolve 1 gm. of potas- 
sium stannosulphate in a solution of 5 gm. of sodium bicar- 
bonate and 5 gm. of potassium and sodium tartrate in 100 ce. 
of water, and titrate the clear liquid with decinormal iodine, 
using starch solution as the indicator. 

1 cc. of decinormal I = 0.019471 gm. of K,Sn(SO,),, lo 
28939. 

POTASSIUM SULPHATE 
K2SO.1. Mol. Wt. 174.36. « 


White, hard crystals, soluble in 10 parts of cold, and in 
4 parts of boiling, water, but insoluble in alcohol. The 
aqueous solution is neutral to litmus paper.’ 


TESTS OF PURITY 


Chlorides, Heavy Metals (Fe, Cu), Calcium, and Magne- 
sium). — 20 cc. portions of the 1: 20 aqueous solution should 
not be affected by hydrogen sulphide water, nor by ammo- 
nium oxalate, silver nitrate, and sodium phosphate solutions. 

Iron. — The solution of 1 gm. of potassium sulphate in 
20 ce. of water boiled with a few drops of nitric acid should 
remain colorless on the addition of potassium sulphocyanate 
solution. 

POTASSIUM SULPHIDE 


Leather-brown or yellowish-green pieces, which deliquesce 
in moist air, dissolve in 2 parts of water with but a slight 
residue, and afford alkaline, yellowish-green solutions. On 
adding acetic acid to the aqueous solution, hydrogen sulphide 
gas is generated in copious quantities. 


POTASSIUM SULPHIDE SOLUTION 


The solution contains 5 per cent of K,S, and is intended 
for use in determining nitrogen according to Kjeldahl. 


182 CHEMICAL REAGENTS 


TEST OF PURITY 


Nitrogen. — Mix 100 cc. of the potassium sulphide solution 
in a distilling flask with 50 cc. of nitrogen-free sodium hy- 
droxide solution (sp. gr. 1.3). Add 1 gm. of zine dust, and 
distil off about 50 cc., collecting the distillate in a U-tube 
receiver containing about 20 cc. of water and 2 to 3 ec. of 
decinormal hydrochloric acid. ‘Titrate the distillate with 
decinormal potassium hydroxide, using methyl orange as the 
indicator. The ammonia distilled over should not have neu- 
tralized more than 0.2 cc. of the decinormal acid. 


POTASSIUM SULPHOCYANATE 


(PorasstuM THIOCYANATE) 
KSCN. Mol. Wt. 97.25. 


Colorless, prismatic crystals, deliquescent in the air, and 
easily soluble in water and in alcohol. 


TESTS OF PURITY 


Substances Insoluble in Alcohol.—1 gm. of potassium 
sulphocyanate should completely dissolve in 10 ce. of boiling 
absolute alcohol, and yield a clear solution. 

Sulphates. — On adding to a solution of 1 gm. of potassium 
sulphocyanate in 20 cc. of water, a few drops of hydrochloric 
acid and some barium chloride solution, no turbidity should 
be observed within five minutes. 

Heavy Metals. — On dissolving 1 gm. of potassium sulpho- 
cyanate in 20 cc. of water, and adding to the solution a few 
drops of ammonium sulphide solution, no precipitate should 
form, nor should a brown or green color develop. 

Iron. — The solution of 1 gm. of potassium sulphocyanate 
in 20 ec. of water should remain perfectly colorless on the 
addition of 0.5 ec. of hydrochloric acid. 


CHEMICAL REAGENTS 183 


POTASSIUM SULPHYDRATE 


(Potassium HyDROSULPHIDE) 
2KSH + HO. Mol. Wt. 162.45. 

Colorless, deliquescent crystals* easily soluble in water and 
in alcohol. The solution is strongly alkaline to litmus paper. 
On boiling, the aqueous solution is decomposed with the 
evolution of hydrogen sulphide gas and the formation of 
potassium hydroxide: 

TEST OF PURITY 


Polysulphides. — The solution of 1 gm. of potassium sul- 
phydrate in 20 cc. of water should be colorless and clear. 
On acidulating the solution with hydrochloric acid, hydrogen 
sulphide gas is generated in copious quantities, and the fluid 
exhibits a slight opalescent turbidity. No separation of 
sulphur should occur. 


POTASSIUM TETRAOXALATE 
KHC.O, + H.C.0, + 2H2O. Mol. Wt: 254.20. 
Colorless, triclinic crystals, soluble in 55 parts of water. 
The aqueous solution is acid to litmus paper. 


TESTS OF PURITY 


The tests for chlorides, sulphates, and heavy metals are — 
to be made as detailed under Potassium Oxalate, Neutral. 

Quantitative Determination. — 

(a) Acidimetric: Dissolve about 3.10 gm. of potassium 
tetraoxalate in water and dilute to 500 cc. Titrate 
50 cc. of this solution, while boiling, with fifth 
normal potassium hydroxide, using phenolphthalein 
as the indicator. 

* When exposed to the air, the preparation rapidly acquires a yellow 


color by taking up oxygen with the formation of polysulphides. It 
should, therefore, be preserved in well-stoppered bottles. 


184 CHEMICAL REAGENTS |, 


1 ce. of fifth normal KOH = 0.016947 gm. of KHC,O, + 
H,C,O, + 2H,0, log. 22909. 

(b) Oxidimetric: To 50 ec. of the solution made for test a, 
add 6 to 8 ec. of concentrated sulphuric acid, heat 
the liquid to about 60° C., and titrate with decinormal 
potassium permanganate. 

1 ce. of decinormal KMnO, = 0.006355 gm. of KHC,O, + 

H,C,0, + 2H,0, log. 80312. 


POTASSIUM AND SODIUM TARTRATE 


(ROCHELLE SALT; SEIGNETTE SALT) 
KNaC.HuO¢ + 4H,0. Mol. Wt. 282.29. 


Colorless, prismatic crystals, soluble in 1.4 parts of water, 
and yielding a neutral solution. 


TESTS OF PURITY 


_ Calcium. — On dissolving 1 gm. of potassium and sodium 

tartrate in 10 cc. of water, and adding to the solution 5 ce. 
of dilute acetic acid, and then shaking for a few minutes, a 
crystalline precipitate forms. On filtering off the latter, 
diluting the filtrate with an equal volume of water, and 
then adding 8 to 10 drops of ammonium oxalate solution, no 
turbidity should develop within one minute. 

Heavy Metals. — The 1:20 aqueous solution should show 
no change with hydrogen sulphide water. 

Chlorides and Sulphates. — The solution of 1 gm. of potas- 
sium and sodium tartrate in 10 ec. of water, with 2 cc. of 
nitric acid added, should not be affected by silver nitrate 


and barium nitrate solutions. 
Ammonium Compounds. — On heating the solution of 1 


em. of potassium and sodium tartrate in 10 cc. of water 
with 10 cc. of sodium hydroxide solution (sp. gr. 1.3), no 
vapors of ammonia should be given off (to be ascertained by 
means of moist litmus paper). 


CHEMICAL REAGENTS 185 


PYROGALLOL 


(Acip PyYRoGALLIC) 
C.H,(OH)s. Mol. Wt. 126.04. 

White, shining needles or scales, melting at 131°C. Pyro- 
gallol is soluble in 1.7 parts of water, in 1 part of alcohol, 
and in 1.2 parts of ether; it is difficultly soluble in benzene, 
chloroform, and carbon disulphide. The aqueous solution is 
slightly acid to litmus paper. 


TESTS OF PURITY 


Inorganic Matter. —1 gm. of pyrogallol, on being heated, 
should volatilize and leave no weighable residue. 

Gallic Acid. — 2 gm. of pyrogallol must completely dissolve 
in 5 ec. of ether (sp. gr. 0.72), and afford a clear solution. 


RESORCINOL 


(RESORCIN) 
CsH.(OH)2. Mol. Wt. 110.04. 


Colorless crystals, having a scarcely perceptible but pecul- 
iar odor, soluble in about 1 part of water, or alcohol, easily 
soluble in ether and in glycerin, difficultly soluble in chlo- 
roform and in carbon disulphide. Resorcinol volatilizes on 
being heated, and melts at 110 to 111° C. The aqueous 
solution is acid to litmus paper. 


TESTS OF PURITY 


Non-volatile Matter. — 1 gm. of resorcinol, on being heated 
and volatilized, should leave no weighable residue. 

Diresorcin and Phenol. — 1 gm. of resorcinol should yield 
a perfectly clear solution with 20 ec. of water; and the solu- 
tion on being warmed should not have a phenolic odor. 

Free Acids (e.g., Salicylic Acid). — On dissolving 1 gm. of 
resorcinol in 10 ec. of alcohol, and adding 1 drop of lacmoid 


186 CHEMICAL REAGENTS 


solution, a wine-red liquid is obtained, which, on the addition 
of 1 drop of decinormal potassium hydroxide, should assume 
a blue color. 


SILVER 
Ag. Atom. Wt. 107.93. 


A white, shining metal in the form of foil, insoluble in 
hydrochloric and in cold dilute sulphuric acids; soluble in 
nitric and in hot concentrated sulphuric acids. 


TESTS OF PURITY 


Foreign Metals. — Dissolve 2 gm. of silver in the smallest 
possible quantity of nitric acid (sp. gr. 1.2). The solution 
should be colorless and there should be no insoluble residue 
(Sb and Sn). Dilute with about 200 cc. of water (no tur- 
bidity should occur after standing one hour — Bi), and pre- 
cipitate the silver by adding hydrochloric acid to the boiling 
solution. Allow the precipitate to settle in a dark place, 
filter, and evaporate the filtrate. No weighable residue 
should remain. 

Quantitative Determination. This may be carried out 
either gravimetrically by precipitating the silver by means of 
hydrochloric acid from a boiling solution slightly acid with 
nitric acid; or the determination may be made volumetrically | 
according to Gay-Lussac’s method, which is used in all the 
laboratories of the German mints. 


Nortr. — Regarding the manner in which this method is carried out, 
see Lunge, Chem.-tech. Untersuch.-Meth., 5 ed., 2, 135; Sutton, Volumet. . 
Anal., 9 ed., p. 303. 

SILVER NITRATE 
AgNOs. Mol. Wt. 169.97: 


Colorless, lustrous crystals or sticks, exhibiting a stellate, 
-erystalline fracture, and yielding a clear, colorless solution 


CHEMICAL REAGENTS 187 


with 0.6 part of water, and with about 10 parts of alcohol. 
The aqueous solution should be neutral to litmus paper. 


TESTS OF PURITY 


Chlorides. — Dissolve 5 gm. of silver nitrate in 5 cc. of 
water, and allow the solution to run into 100 cc. of water. 
No turbidity or opalescence should occur. 

Potassium Nitrate. — Dissolve 0.5 gm. of silver nitrate in 
0.5 ec. of water, mix the solution with 20 cc. of absolute 
alcohol, and shake for a few minutes. No turbidity or 
precipitate should form. 

Salts of Copper, Bismuth, and Lead. — Dissolve 1 gm. of 
silver nitrate in 5 ec. of water, and add to the solution 10 ce. 
of ammonia water. The liquid should remain clear and 
colorless. 

Substances not Precipitated by Hydrochloric Acid. — Dissolve 
2 gm. of silver nitrate in 50 cc. of water, heat the solution 
to boiling, and add 3 cc. of hydrochloric acid. After the 
precipitate has settled, filter, and evaporate the filtrate to 
dryness. No weighable residue should remain. 

Quantitative Determination. — This is carried out as de- 
tailed under Silver. 


SILVER NITRITE 
AgNO». Mol. Wt. 153.97. 
Small, yellowish, acicular crystals, soluble in about 300 
parts of cold water. Silver nitrite is more readily soluble in 
hot water, but suffers partial decomposition therein. 


TESTS OF PURITY 


Substances not Precipitated by Hydrochloric Acid. — Dissolve 
2 gm. of silver nitrite, with heat, in 100 cc. of water, with 
the aid of 2 cc. of nitric acid, heat the solution to boiling, 
and add 3 ec. of hydrochloric acid. After the precipitate 


188 CHEMICAL REAGENTS 


has settled, filter, and evaporate the filtrate to dryness. No 
weighable residue should remain. 

Quantitative Determination.* — Dissolve 1.5 gm. of silver 
nitrite in water and dilute to 500 cc. Make a mixture 
containing 18 to 19 cc. of decinormal potassium permanganate 
solution, 20 ec. of dilute sulphuric acid, and 300 cc. of water, 
heat it to 40 to 50° C., and run the nitrite solution into it 
until the pink color just disappears. Care must be taken 
towards the end to introduce the nitrite solution very slowly, 
because the change from pink to colorless always requires 
some time. 

1 ec. of decinormal KMnO, = 0.0076985 gm. of AgNO,, 
log. 88640. 

SODIUM 
Na. Atomic Wt. 23.05. 

The metal, when freshly cut, has a silver-white surface, 
which rapidly becomes dull on exposure to air and becomes 
covered with crusts of sodium oxide, sodium hydroxide, and 
sodium carbonate. At ordinary temperatures, sodium has 
the consistency of wax, but at low temperatures it is brittle. 

TESTS OF PURITY 

. Foreign Metals. — 

(a) 1 gm. of sodium is freed from ee petroleum by 
wiping with pieces of filtering paper, then cut into 
small pieces, and thrown upon 20 cc. of cold water. 
The solution of sodium hydroxide so obtained should 
appear unchanged upon adding ammonium sulphide 
solution. 

(b) The solution perpared from 1 gm. of sodium and 20 ce. 
of water should be unchanged in appearance on the 
addition of 10 ec. of hydrochloric acid, followed by 
hydrogen sulphide water. 


* Compare other methods of determining nitrites; Sutton, Volumet. 
Anal., 9 ed., p. 270 (1904). 


CHEMICAL REAGENTS 189 


SODIUM ACETATE 
NaC:H;02 se 3H.0. Mol. Wt. 136.12. 


Colorless, transparent crystals, efflorescent in warm air, 
soluble in 1 part of water, in 23 parts of cold, and 1 part of 
boiling, alcohol. 

The solution of 1 gm. of sodium acetate in 1 cc. of water 
is alkaline to litmus paper; it should, however, not be red- 
dened, or only very slightly, by phenolphthalein solution. 


TESTS OF PURITY 


Chlorides. — The solution of 1 gm. of sodium acetate in 
20 ce. of water should appear unchanged on adding 1 ce. of 
nitric acid followed by silver nitrate solution. | 

Sulphates. — 20 cc. of the 1:20 aqueous solution should 
not be rendered turbid by barium chloride solution. 

Heavy Metals and Calcium. — 20 cc. of the 1:20 aqueous 
solution should not be affected by hydrogen sulphide water, 
nor by ammonium oxalate solution. 

Iron. — The solution of 1 gm. of sodium acetate in 20 ce. 
of water should not be reddened on adding 1 ce. of hydro- 
chloric acid, followed by potassium sulphocyanate solution. 


SODIUM AMALGAM 


Gray pieces, the size of peas, containing 2 per cent of 
metallic sodium. 
TEST OF STRENGTH 


Quantitative Determination of Sodium. — Introduce 10 gm. 
of sodium amalgam into 100 cc. of water, and allow the 
mixture to stand with repeated shaking until the evolution 
of hydrogen entirely ceases. Then titrate with normal 
hydrochloric acid, using methyl orange as the indicator. 

1 ec. of normal HCl = 0.02305 gm. of Na, log. 36267. 


190 CHEMICAL REAGENTS 


SODIUM BICARBONATE 
NaHCOs;. Mol. Wt. 84.05. 


White, crystalline crusts, or crystalline powder, soluble in 
12 parts of water, but insoluble in alcohol. The aqueous 
solution is faintly alkaline to litmus paper. — 


TESTS OF PURITY 


Sulphates. — Dissolve 2 gm. of sodium bicarbonate in 30 ce. 
of water, add 10 ce. of hydrochloric acid, heat to boiling, 
and add barium chloride solution. No precipitate of barium 
sulphate should form within twelve hours. 

Silica. — Dissolve 5 gm. of sodium bicarbonate in 15 ce. 
of water and 25 ec. of hydrochloric acid in a platinum dish. 
Evaporate the solution on the water-bath, dry the residue 
for half an hour at 120° C., and then dissolve it in 3 ce. of 
hydrochloric acid and 25 cc. of water. The solution should 
be perfectly clear. 

Chlorides, Thiosulphates, and Arsenic. — On adding to the 
solution of 1 gm. of sodium bicarbonate in 50 cc. of water 
5 ec. of dilute acetic acid, followed by silver nitrate solution, 
at most a faint opalescence should develop. 

Phosphates. — Dissolve 2 gm. of sodium bicarbonate in 
20 ce. of water, add 20 ce. of nitric acid and 10 cc. of ammo- 
nium molybdate solution. On heating to 30 to 40° C., no 
yellow precipitate should form within two hours. 

Heavy Metals. — 

(a) The solution of 3 gm. of sodium bicarbonate in 40 ce. 
of water and 8 cc. of hydrochloric acid should 
remain unchanged on the addition of hydrogen sul- 
phide water; on adding to the liquid 5 cc. of am- 
monia water and a few drops of ammonium sulphide 
solution, no precipitate should form, nor should a 
green or brown color develop. 


CHEMICAL REAGENTS 191 


(b) The solution of 1 gm. of sodium bicarbonate in 15 ce. 

- of water and 2 cc. of hydrochloric acid should not 

be reddened on the addition of potassium sulpho- 
cyanate solution. 

Potassium. — The yellow color imparted by sodium bicar- 
bonate to the flame, when observed through cobalt glass, 
should have at most a transient violet tinge. 

Monocarbonate (Neutral Sodium Carbonate). — 

(a) A solution of 1 gm. of sodium bicarbonate in 20 cc. of 
water, prepared at a temperature not above 15°.C., 
without excessive shaking, should not be imme- 
diately reddened on the addition of 3 drops of 
phenolphthalein solution; at all events, any slight 
redness that may develop should disappear on the 
addition of 0.2 ec. of normal hydrochloric acid. 

(b) 1 gm. of the sodium bicarbonate dried over sulphuric 
acid, and ignited, should leave a residue weighing 
not more than 0.638 gm. 

Ammonia. — On heating 1 gm. of sodium bicarbonate in a 
test-tube, no vapors of ammonia should be evolved (to be 
ascertained by moistened turmeric paper). 

Sulphocyanates. — The solution of 1 gm. of sodium bicar- 
bonate in 3 cc. of nitric acid and 47 ce. of water should not 
be reddened on the addition of 1 drop of ferric chloride 
solution. 

Quantitative Determination. — On titrating 1 gm. of sodium 
bicarbonate with normal hydrochloric acid, using methyl 
orange as the indicator, 11.9 ce. of the acid should be required. 
1 cc. of normal HCl = 0.08405 gm. of NaHCO,, log. 92454. 


192 CHEMICAL REAGENTS 


SODIUM BISULPHATE 


(Soprum Acip SULPHATE) 
NaHSO, + H:O. Mol. Wt. 138.13. 


Colorless crystals, or white, fused pieces, easily soluble in 
water. The aqueous solution is strongly acid to litmus paper. 


TESTS OF PURITY 


Heavy Metals. — The solution of 1 gm. of sodium bisul- 
phate in 20 ec. of water should not be affected by hydrogen 
sulphide water; nor should it show any change on making it 
alkaline with ammonia water, and then adding ammonium 

sulphide solution. 

Chlorides. — 20 cc. of the 1:20 aqueous solution should 
not be rendered turbid on adding silver nitrate solution. 

Arsenic. — The mixture of 1 gm. of powdered sodium 
bisulphate with 3+ cc. of stannous chloride solution should 
not acquire a darker color within one hour. 

Potassium. — The yellow-colored flame produced by sodium 
bisulphate, when observed through cobalt eww should exhibit 
only a transient violet color. | 

Quantitative Determination. — Dissolve 1 gm. of sodium 
bisulphate in 50 cc. of water, and titrate with normal potas- 
sium hydroxide, using methyl orange as the indicator. 

1 cc. of normal KOH = 0.13813 gm. of NaHSO, + H,0, 
log. 14029. oo 


SODIUM BISULPHITE 


(Soprum AciIp SULPHITE) 
NaHSOs;. Mol. Wt. 104.118. 
A white powder, having an odor of sulphurous acid, and 
soluble in 4 parts of water. The aqueous solution is acid to 
litmus paper. 


CHEMICAL REAGENTS 193 


TESTS OF PURITY 


Heavy Metals and Arsenic. — Completely evaporate a mix- 
ture of 5 gm. of sodium bisulphite with 5 cc. of pure sulphuric 
acid (sp. gr. 1.84) on the sand-bath, and dissolve the residue 
in 20 ec. of water. 10 cc. of this solution should not be 
affected by hydrogen sulphide water. On adding to the 
other 10 cc. of the solution a solution of ammonium molybdate 
in nitric acid, and heating the mixture to 70 to 80° C., the 
liquid should not acquire a yellow color, nor should a yellow 
precipitate form. 

Quantitative Determination. — Dissolve 1 gm. of sodium 
bisulphite in thoroughly boiled water and dilute to 100 ce. 
Run this solution from a burette into a mixture of 30. cc. of 
decinormal iodine and 5 cc. of hydrochloric ‘acid, with con- 
stant shaking, until complete decoloration ensues. 

1 cc. of decinormal I = 0.0052059 gm. of NaHSO,, log. 
71649. 


SODIUM BORATE, CRYSTALS 


(Borax; Soprum TETRABORATE; SopruM BIBoRATE) 
NazB.O7 + 10 H.O. Mol. Wt. 382.26. 


Hard, colorless crystals, or crystalline pieces, soluble in 
17 parts of cold, and in 0.5 part of boiling, water, freely 
soluble in glycerin, but insoluble in aleohol. When borax 
is heated, it swells up, the water of crystallization being 
expelled, and at a red heat the anhydrous borax fuses to a 
transparent, colorless mass. 

The aqueous solution is alkaline to litmus paper, and 
when acidulated with hydrochloric acid it colors turmeric 
paper brown. The brown color becomes particularly evident 
as the paper dries, and when moistened with ammonia water 
the color becomes greenish-black. 


194 CHEMICAL REAGENTS 


I 
SODIUM BORATE 
TESTS OF PURITY 


Carbonates and Sulphates. — The solution of 1 gm. of borax 
in 20 cc. of water should not effervesce on the addition of 
hydrochloric acid, and should not be affected by the subse- 
quent addition of barium chloride solution. 

Chlorides. — On adding to 20 cc. of the 1:20 aqueous 
solution 3 ec. of nitric acid, followed by silver nitrate solu- 
tion, at most a slight opalescent turbidity should develop. 

Quantitative Determination.* — Dissolve 1 gm. of borax in 
50 ec. of water, add 1 drop of methyl orange solution, and 
titrate with fifth normal hydrochloric acid. 

1 ce. of fifth normal HCl = 0.038226 gm. of Na,B,O, + 
10H,0, log. 58235. 

II 


SODIUM BORATE, PUREST CRYSTALS 


TESTS OF PURITY 


Content of Water.j — 1 gm. of borax, on ignition, should ~ 
yield a residue weighing 0.529 gm. 

Carbonates and Sulphates. — The solution of 1 gm. of borax 
in 20 ce. of water should not effervesce on adding 1 cc. of 
hydrochloric acid, nor should it become turbid on the subse- 
quent addition of barium chloride solution. 

Chlorides. — On adding to 20 cc. of the 1:20 aqueous 
solution 3 ec. of nitric acid, followed by silver nitrate solu- 
tion, no change should appear. 

* Compare method of Schwartz as given in Sutton, Volumet. Anal., 
9 ed., p. 94 (1904). 

+ Besides this prismatic borax containing 10 molecules of water of 


crystallization, there is another borax containing 5 molecules of water 
of crystallization, crystallizing in octahedra. 


CHEMICAL REAGENTS 195 


Calcium. — The solution of 1 gm. of borax in 20 ee. of 
water should not be rendered turbid by ammonium oxalate 
solution. 

Iron and Other Metals. — 

(a) The solution of 1 gm. of borax in 20 cc. of water 
should not be reddened on the addition of 2 ec. of 
hydrochloric acid, followed by potassium sulpho- 
cyanate solution. 

(b) 20 ec. of the 1:20 aqueous solution, acidulated with 
2 cc. of hydrochloric acid (sp. gr. 1.124), should 
remain unchanged on the addition of hydrogen 
sulphide water. 

Quantitative Determination. — The determination is carried 

out as detailed under Sodium Borate. | 


SODIUM BORATE, PUREST, CALCINED. 


A white, spongy mass, or white powder, containing at least 
75 per cent of Na,B,O, (anhydrous). 


TESTS OF PURITY 


The tests to be made are those given under Sodium Borate, 
Purest, Cryst. But for each gram of crystallized borax use 
0.7 gm. of the calcined. 

Quantitative Determination.* — Dissolve 1 gm. of calcined 
borax in 50 ce. of water, add 1 drop of methyl orange solution, 
and titrate with fifth normal hydrochloric acid. At least 
37.2 ec. of the acid should be necessary to produce the end- 
point. 

1 ec. of fifth normal HCl = 0.02021 gm. of Na,B,0O,, log. 
30557. 


* Compare methods given by Sutton, Volumet. Anal., 9 ed., p. 94 (1904). 





A BRAR 
OF THE 


UNIVERSITY 
: OF 


CALIFORNIA 


ene Te 





196 CHEMICAL REAGENTS 


SODIUM BORATE, PUREST, FUSED 


(Borax Guass; ANHYDROUS Borax) 
NavB,O7. Mol. Wt. 202.1. 


Colorless, vitreous pieces, which take up moisture from the 
air, and in consequence become opaque. 


TESTS OF PURITY 


The tests to be made are those given under Sodium Borate, 
Purest, Cryst. But for each gram of the crystallized borax 
use 0.5 gm. of the fused. 

Quantitative Determination. — This is carried out as de- 
scribed under Sodium Borate, Purest, Calcined. 


SODIUM BROMATE 
NaBrOs. Mol. Wt. 151.01. 


Shiny crystals, or crystalline powder, soluble in 3 parts of 
cold, and in about 1.5 parts of boiling, water. 


TESTS OF PURITY 


Bromides. — On dissolving 2 gm. of sodium bromate in 
20 cc. of water, and adding 5 ce. of dilute sulphuric acid, 
the solution should not immediately acquire a yellow color. 

Quantitative Determination. — Dissolve 0.10 to 0.15 gm. 
of sodium bromate, previously dried for twenty-four hours 
over sulphuric acid, in 20 ec. of water, add 3 gm. of potassium 
iodide and 5 cc. of hydrochloric acid, and titrate the liberated 
iodine with decinormal sodium thiosulphate. 

1 ec. of decinormal Na,S,0, = 0.002517 gm. of NaBrO,, 
shes 40088. 


CHEMICAL REAGENTS 197 
SODIUM CARBONATE 


I 


SODIUM CARBONATE, CRYSTALS 
Na2CO3; + 10H20. Mol. Wt. 286.26. 


Colorless, transparent crystals, efflorescent in the air, sol- 
uble in 1.6 parts of cold, and 0.2 part of boiling, water. The 
aqueous solution is strongly alkaline to litmus paper. Sodium 
carbonate is insoluble in alcohol. The crystallized sodium 
carbonate contains 37 per cent of the anhydrous salt, Na,CO,. 


TESTS OF PURITY 


Substances Insoluble in Water. — 20 gm. of sodium car- 
bonate should completely dissolve in 80 cc. of water, yielding 
a perfectly colorless solution. 7 

Sodium Hydroxide. —In a graduated flask of 100 ce. 
capacity, dissolve 3 gm. of crystallized sodium carbonate in 
50 cc. of water, add to the solution 6 gm. of crystallized 
barium chloride dissolved in 30 cc. of water, and then fill 
with water up to the mark. After thoroughly shaking, 
filter, and to 50 cc. of the filtrate add some phenolphthalein 
solution. The liquid should not acquire a red color. Use 
boiled water throughout. 

Sulphates. — On boiling a solution of 10 gm. of sodium 
carbonate in 50 cc. of water and 10 ce. of hydrochloric acid, 
for a few minutes, and then adding barium chloridesolution, 
no precipitate of barium sulphate should form within twelve 
hours. 

Chlorides. — The solution of 5 gm. of sodium carbonate 
in 50 ee. of water and 10 ce. of nitric acid should not be 
affected by silver nitrate solution. 

Silicates. — Dissolve 20 gm. of crystallized sodium carbo- 
nate in 30 ec. of hydrochloric acid in a platinum dish, and 


198 CHEMICAL REAGENTS 


evaporate the solution on the water-bath to dryness. Dry 
the residue half an hour at 120° C., and then dissolve it in 
3 ec. of hydrochloric acid and 50 ec. of water. The solution 
should be perfectly clear. 

Nitrates. — Dissolve 1 gm. of sodium carbonate in 10 ce. 
of dilute sulphuric acid, and overlay this liquid on 5 ce. of a 
solution of 0.5 gm. of diphenylamine in 100 ce. of concen- 
trated sulphuric acid and 20 cc. of water. No blue color 
should form at the contact-surfaces of the two liquids. 

Phosphates. — To the solution of 20 gm. of sodium carbo- 
nate in 50 ee. of nitric acid add 50 ce. of a solution of am- 
monium molybdate in nitric acid. No yellow precipitate 
should form in the liquid on standing two to three hours 
at about 40° C. 

Potassium. — The yellow color imparted by sodium carbo- 
nate to the flame, when observed through cobalt glass, should 
at most have a transient violet tinge. 

Ammonium Compounds. — On adding 1 cc. of Nessler’s 
reagent to a solution of 10 gm. of sodium carbonate in 50 ce. 
of water, no change should be observed. 

Calcium and Magnesium. — Dissolve 10 gm. of sodium 
carbonate in 10 cc. of water and 10 ce. of hydrochloric acid, 
and add 5 cc. of ammonia water, followed by ammonium 
oxalate solution. The liquid should remain perfectly clear, 
and should show no change even on the addition of ammo- 
nium phosphate solution and standing for several hours. 

Heavy Metals. — 

(a) The solution of 20 gm. of sodium carbonate in 50 cc. 
of water and 20 ce. of hydrochloric acid should not 
be affected by hydrogen sulphide water; on now 
adding to the solution 5 ec. of ammonia water and 
a few drops of ammonium sulphide solution, no 
turbidity or green color should develop. 

(b) A solution of 10 gm. of sodium carbonate in 25 cc. of 


CHEMICAL REAGENTS 199 


water and 10 cc. of hydrochloric acid should not 
acquire a red color on the addition of potassium 
sulphocyanate solution. 

Arsenic. — Introduce 20 gm. of arsenic-free, metallic zine 
into the generating flask of a Marsh apparatus, and start the 
hydrogen by adding dilute sulphuric acid (1:5). Dissolve 
30 gm. of sodium carbonate in 100 ec. of dilute sulphuric 
acid (1:5), introduce the solution in small quantities at a 
time into the Marsh apparatus, and maintain a slow stream 
of gas for about half an hour. At the close of this period no 
deposit of arsenic should be visible within the reduction 
tube. 

Quantitative Determination. — Dissolve 3 gm. of sodium 
carbonate in 50 cc. of water, and titrate with normal hydro- 
chloric acid, using methyl orange as the indicator. 

1 cc. of normal HCl = 0.14313 gm. of Na,CO, + 10H,O, 
log. 15573. 

II 


SODIUM CARBONATE, DRIED 


A white, dry powder, containing about 80 per cent of 
Na,CO,. : 
TESTS OF PURITY 

The tests to be made are those given under Sodium Carbo- 
nate Crystals. But for each gram of the crystals use 0.45 
gm. of the dried. 

Quantitative Determination. — Dissolve 1 gm. of the so- 
dium carbonate in 50 ec. of water, and titrate with normal 
hydrochloric acid, using methyl orange as the indicator. At 
least 15 cc. of normal acid should be required. — 

1 cc. of normal HCl = 0.05305 gm. of Na,CO,, log. 72469. 


200 CHEMICAL REAGENTS 


‘Ill 


SODIUM CARBONATE, ANHYDROUS 
Na:CO3. Mol. Wt. 106.1 


A white powder, containing 99 to [00 per cent of Na,CO,.* 
TESTS OF PURITY 


The tests to be made are those given under Sodium Car- 
bonate Crystals. But for each gram of crystals use 0.35 gm. 
of the anhydrous. 

Quantitative Determination. — Dissolve 1 gm. in 50 cc. of 
water and titrate with normal hydrochloric acid, using methyl 
orange as indicator. At least 18.7 cc. of the normal acid 
should be required. 

1 cc. of normal HCl = 0.05305 gm. of Na,CO,, log. 72469. 


SODIUM CHLORIDE 
NaCl. Mol. Wt. 58.5. 


I 
' SODIUM CHLORIDE 


White, cubical crystals, or crystalline powder, soluble in 
2.7 parts of water. The aqueous solution is neutral to litmus 


paper. 
TESTS OF PURITY 


Sulphates. —3 gm. of sodium chloride yield a perfectly 
clear solution with 20 cc. of water. On diluting this solu- 
tion with 80 ec. of water, adding 1 cc. of hydrochloric acid, 
heating to boiling, and then adding barium chloride solution, 
no precipitate of barium sulphate should form within twelve 
hours. 


* Sodium carbonate, which is to be used as a standard in volumetric 
determinations, must first be heated for thirty minutes in a sand-bath, 
or in an air-bath, at 270 to 300° C. (See Lunge, Ztschr. angew. Chem., © 
17, 231 (1904); J. Chem. Soc., 86, II, 289 (1904) .) 


CHEMICAL REAGENTS 201 


Alkaline Earths, and Heavy Metals. — The solution of 3 gm. 
of sodium chloride in 50 ce. of water, heated to boiling, 
should not be affected by ammonium oxalate solution; nor 
by sodium carbonate solution; nor by ammonium sulphide 
solution. | 

Magnesium. — Dissolve 3 gm. of sodium chloride in 10 ce. 
of water, and add 5 cc. of ammonia water and ammonium 
phosphate solution. No precipitate should form within three 
hours. | 

Iodides. — On adding to 20 cc. of the 1:20 aqueous solu- 
tion one drop of ferric chloride solution and some starch 
solution, no blue color should develop. 

Potassium. — On adding platinic chloride solution and 3 ce. 
of alcohol (95 per cent) to the solution of 1 gm. of sodium 
chloride in 5 cc. of water, no precipitate should form within 
two hours. 3 

Iron. — The solution of 3 gm. of sodium chloride in 20 ce. 
of water boiled with a few drops of nitric acid should not 
acquire a red color on the addition of potassium sulphocyanate 
solution. 

Ammonium. — The solution of 3 gm. of sodium chloride 
in 20 cc. of water should not be changed in appearance on 
the addition of Nessler’s reagent. 

Quantitative Determination. — Dissolve 0.2 gm. of sodium 
chloride in 100 ce. of water, add a few drops of potassium 
chromate solution, and titrate with decinormal silver nitrate 
solution until a permanent red precipitate Just begins to form. 

1 ce of decinormal AgNO, = 0.00585 gm. of NaCl, log. 
76716. 


II 
SODIUM CHLORIDE, FUSED 


Colorless, translucent pieces. 


202 CHEMICAL REAGENTS 


TESTS OF PURITY 


The tests and the quantitative determination as given 
under Sodium Chloride are to be made. 


SODIUM HYDROXIDE 


(Caustic Sopa; Soprum HypratE) 
NaOH. Mol. Wt. 40.058. 


Three grades of sodium hydroxide are used in the chemical 
laboratory : 

1. Sodium Hydroxide, from Sodium. 

2. Sodium Hydroxide, Purified by Alcohol. 

3. Sodium Hydroxide, Purified. 

These three preparations vary chiefly in their content of 
chloride, sulphate, silica, and alumina. 


I 
- SODIUM HYDROXIDE, FROM SODIUM 


White pieces showing a crystalline structure on fracture. 
The preparation contains from 95 to 98 per cent of NaOH. 


TESTS OF PURITY 


Sulphates. — Dissolve 3 gm. of sodium hydroxide in 50 ce. 
of water, acidulate with 15 ec. of hydrochloric acid, heat to 
boiling, and add barium chloride solution. No precipitate 
of barium sulphate should form within twelve hours. 

Chlorides. — Dissolve 1 gm. of sodium hydroxide in 20 ce. 
of water, add 10 cc. of nitric acid and a few drops of silver 
nitrate solution. At most a slight opalescent turbidity should 
develop. 

Nitrogen as Nitrates, Nitrites, Ammonia, etc. — 

(a) To 2 gm. of sodium hydroxide dissolved in 10 cc. of 

water add 20 cc. of dilute sulphuric acid, 1 drop of 


CHEMICAL REAGENTS 203 


1: 1000 indigo solution, a granule of sodium chloride, 
and then 10 ec. of concentrated sulphuric acid. The 
blue color of the mixture should not disappear 
within ten minutes. 

(b) Dissolve 25 gm. of sodium hydroxide in 100 cc. of 
water in a distillation flask, and add 5 gm. of zine 
dustand 5 gm. of iron by hydrogen. Connect the flask 
with a condenser and a U-tube receiver containing 
3 to 5 ce. of fifth normal hydrochloric acid and 10 ce. 
of water, allow to stand for several hours, and then 
distil off about 25 ec. over a small flame.  Titrate 
the distillate with fifth normal potassium hydroxide, 
using methyl orange as the indicator. At most 
0.2 cc. of the acid should have been mranires to 
neutralize the ammonia. 

Silica. — Dissolve 5 gm. of sodium hydroxide in 25 ec. of 
water and 25 cc. of hydrochloric acid in a platinum dish, 
and evaporate to dryness on a water-bath. Dry the residue 
for half an hour on the sand-bath at about 120° C., and then 
dissolve it in 10 ec. of hydrochloric acid and 90 cc. of water. 
Any insoluble residue should be filtered off, washed, and 
ignited. Its weight should not exceed 0.0005 gm. 

Alumina, Calcium, and Heavy Metals. — 5 gm. of sodium 
hydroxide should afford a clear and colorless solution with 
10 cc. of water. To this solution add 30 ce. of acetic acid 
(sp. gr. 1.041), followed by 10 cc. of ammonia water. Then 
dilute with 55 ec. of water, and heat the liquid on the water- 
bath until the odor of ammonia has disappeared. Add 2 to 
3 drops of ammonia water, and allow to stand twelve hours. 
Within this time, no precipitate, or only a very slight floc- 
culent precipitate, should form. In the latter case, the 
precipitate is filtered off and washed. Its weight upon 
ignition should not’ exceed 0.0005 gm. With the filtrate, 
the following tests are made: 


204 CHEMICAL REAGENTS 


To 50 cc. add a few cubic centimeters of ammonium oxalate 
solution. No precipitate of calcium oxalate should form on 
standing two hours. 

To another 50 cc. add a few drops of ammonium sulphide 
solution; no change should appear. 

Quantitative Determination and Determination of Sodium 
Carbonate Content. — Titrate the solution of 1 gm. of sodium 
hydroxide in 100 ec. of water with normal hydrochloric acid 
in the cold, using phenolphthalein as indicator. At least 
24 cc. of normal acid should be required to destroy the red 
color. Now add 1 drop of methyl orange, and titrate further 
until the color changes to red. In the second titration, at 
most 0.3 ec. of acid should be used (3.18 per cent of Na,CO,).* 

1 cc. of normal HCl = 0.04005 gm. of NaOH, log. 60260. 

1 cc. of normal HCl = 0.05305 gm. of Na,CO,, log. 72469. 


II 
SODIUM HYDROXIDE, PURIFIED BY ALCOHOL 


White, very hygroscopic sticks or pieces, exhibiting a 
crystalline fracture. The preparation contains 95 to 98 per 
cent of NaOH. 

TESTS OF PURITY 

Sulphates. — Dissolve 3 gm. of sodium hydroxide in 50 ce. 
of water, acidulate with 15 ec. of hydrochloric acid, heat to 
boiling, and add barium chloride solution. The liquid should 
not have more than a slight turbidity; and it should still be 
transparent when observed in a test-tube of 2 cm. diameter. 

Chlorides. — The solution of 1 gm. of sodium hydroxide 
in 20 ec. of water and 10 cc. of nitric acid may be rendered 
opalescent on adding a few drops of silver nitrate solution, 
but should develop no precipitate. 


* Regarding the calculation of the sodium carbonate, see the note 
under Potassium Hydroxide, Purest. 


CHEMICAL REAGENTS 205 


Nitrogen as Nitrates, Nitrites, Ammonia, etc.— The test is 
carried out as detailed under Sodium Hydroxide, From 
Sodium. 

Silica. — Dissolve 5 gm. of sodium hydroxide in 25 ce. of 
water with 25 ec. of hydrochloric acid in a platinum dish, 
and evaporate to dryness on the water-bath. Dry the 
residue on the sand-bath for half an hour at about 120° C., 
and then dissolve it in 10 ec. of hydrochloric acid and 90 ee. 
of water. Any insoluble residue is filtered off, washed, and 
ignited. Its weight after ignition should not exceed 0.0025 
om. 

Alumina, Calcium, and Heavy Metals. — 5 gm. of sodium 
hydroxide should afford a clear and colorless solution with 
20 ce. of water. Dilute the solution to 100 ec., and then add 
30 ec. of acetic acid (sp. gr. 1.041) and 10 ec. of ammonia 
water. At most a slight turbidity should develop within 
five minutes, but no flocculent precipitate of aluminum 
hydroxide should form; nor should an immediate change in 
appearance occur on the addition of ammonium oxalate and 
ammonium sulphide solution. 

Quantitative Determination. — This is carried out as de- 
scribed under Sodium Hydroxide, From Sodium. The amount 
_ of sodium carbonate present should not exceed 4 per cent. 


Il 
SODIUM HYDROXIDE, PURIFIED 


White, very hygroscopic sticks or pieces, exhibiting a 
crystalline fracture. The preparation contains 90 to 95 per 
cent of NaOH. a 
TESTS OF PURITY 

Nitrogen as Nitrates and Nitrites. — To the solution of 2 gm. 
of sodium hydroxide in 10 ce. of water, add 15 ee. of 16 per 
cent sulphuric acid, 1 drop of 1:1000 indigo solution, a granule 


206 CHEMICAL REAGENTS 


of sodium chloride, and then 10 cc. of concentrated sulphuric 
acid. The blue color of the mixture should not disappear 
within ten minutes. 

Alumina, Calcium, and Heavy Metals. — 2.5 gm. of sodium 
hydroxide should afford a clear and colorless solution with 
10 cc. of water. Dilute the solution to 100 cc. and add 15 ee. 
of acetic acid (sp. gr. 1.041) and 5 ce. of ammonia water. 
At most a slight turbidity should develop within five minutes, 
but no flocks of aluminum hydroxide should separate. The 
solution thus tested should not immediately be rendered 
turbid on the addition of ammonium oxalate solution; and 
on adding to it ammonium sulphide solution, it should acquire 
at most a slight green color. 

Quantitative Determination and Determination of the So- 
dium Carbonate Content. — Titrate a solution of 1 gm. of 
sodium hydroxide in 100 cc. of water with normal hydro- 
chloric acid in the cold, using phenolphthalein as the indi- 
eator. At least 22.5 cc. of normal acid should be required 
to discharge the color. Now add 1 drop of methyl orange, 
and titrate further until the color again changes to red. In 
this second titration at most 0.5 ec. of the acid should be 
necessary (5.3 per cent of Na,CO,).* 

1 ec. of normal HCl = 0.04005 gm. of NaOH, log. 60260... 

1 ec. of normal HCl = 0.05305 gm. of Na,CO,, log. 72469 


* Regarding the calculation of the sodium carbonate, see the note 
under Potassium Hydroxide, Purest. 


CHEMICAL REAGENTS 207 


SODIUM HYROZIDE SOLUTIONS 


(Caustic Sopa SOLUTIONS) 


I 


SODIUM HYDROXIDE, SOLUTION I—FREE FROM 
NITROGEN 


‘A colorless liquid of specific gravity 1.3, and containing 
about 27 per cent of sodium hydroxide, NaOH. 


TESTS OF PURITY 


Nitrogen of Nitrates, Nitrites, Ammonia, etc.—The test for 
nitrogen is carried out by the distillation method as described 
under Sodium Hydroxide, From Sodium. For this purpose 
70 ec. (90 gm.) of sodium hydroxide, solution I, should be 
taken. | : 

II 


SODIUM HYDROXIDE, SOLUTION II— FREE FROM 
NITROGEN 


A colorless liquid of specific gravity 1.3 and containing 
about 27 per cent of sodium hydroxide, NaOH. 
TESTS OF PURITY 


The tests to be made are those given under Sodium Hy- 
droxide, Purified by Alcohol. But for each gram of sodium 
- hydroxide, purified by alcohol, yse 2.9 ec. (8.7 gm.) of 
sodium hydroxide, solution II, N-free. 


Ill 
SODIUM HYDROXIDE, SOLUTION III. SP. GR. 1.168 


A clear, colorless liquid, of specific gravity 1.168 to 1.172, 
and containing about 15 per cent of sodium hydroxide, NaOH. 


208 CHEMICAL REAGENTS 


TESTS OF PURITY 


The tests to be made are those given under Sodium Hy- 
droxide, Purified by Alcohol. But for each gram of sodium 
hydroxide, purified by alcohol, use 5.6 cc. (6.5 gm.) of 
sodium hydroxide, solution III. : 


SODIUM HYDROXIDE WITH LIME 


(Sopa-LIME) 


: 
SODIUM HYDROXIDE WITH LIME 


A white, porous mass, finely or coarsely granulated. 


TESTS OF PURITY 


Excess of Carbonate. — Soda-lime, when treated with dilute 

sulphuric acid, should not effervesce strongly. 

Nitrogen. — 

(a) On igniting soda-lime in a test-tube, it should develop 
no vapors of ammonia (to be ascertained by moist- 
ened litmus paper). 

(b) Shake 50°gm. of finely powdered soda-lime with a mix- 
ture of 5 gm. of zinc dust and 5 gm. of iron by 
hydrogen in 200 ce. of water in a flask of about 
500 cc. capacity. Connect the flask with a condenser 
and a receiver containing 2 to 3 cc. of fifth normal 
hydrochloric acid, allow to stand for two to three 
hours, and then distil off about 25 ce. over a small 
flame. Now titrate the distillate with fifth normal 
potassium hydroxide, using methyl orange as the 
indicator. No more than 0.2 ec. of the acid should 
have been required to neutralize the ammonia. 


CHEMICAL REAGENTS 209 


II 


SODIUM HYDROXIDE WITH LIME FROM ICELAND 
SPAR 


A white, porous, granular mass. © 
TESTS OF PURITY 


Chlorides. — Dissolve 5 gm. of soda-lime in 50 ce. of 

nitric acid, and dilute the solution with I00 cc. of water. 
The liquid should acquire at most a slight opalescent tur- 
bidity on the addition of silver nitrate solution. 
- Phosphorus. — Dissolve 10 gm. of soda-lime in 100 ce. of 
nitric acid, and add to the solution 25 cc. of a solution of 
ammonium molybdate in nitric acid. No yellow precipitate 
should form within two to three hours on standing at about 
40° C. 

Sulphur. — Thoroughly mix 5 gm. of finely powdered soda- 
lime with 2 gm. of sodium nitrate, and ignite the mixture in. 
a silver crucible. Dissolve the melt in 50 ec. of water with 
20 ec. of hydrochloric acid, filter, and to the filtrate add 
barium chloride solution. No precipitate of barium sulphate 
should form within twelve hours. 


SODIUM NITRATE 
NaNO;. Mol. Wt. 85.09. 


Colorless, transparent, rhombohedrie crystals, soluble in 
1.2 parts of water and in 50 parts of alcohol. The aqueous 
solution is neutral to litmus paper. 


TESTS OF PURITY 


Sulphates. — On dissolving 3 gm. of sodium nitrate in 
60 cc. of water, and adding 0.5 cc. of hydrochloric acid fol- 
lowed by barium chloride solution, no precipitate of barium 
sulphate should form on standing twelve hours. 


210 , CHEMICAL REAGENTS 


Chlorides. — The solution of 1 gm. of sodium nitrate in 
20 cc. of water, acidulated with a few drops of nitric acid, 
should not be rendered turbid on the addition of silver nitrate 
solution. 

Chlorates and Perchlorates. — On gently igniting 1 gm. of 
sodium nitrate, dissolving the residue in 20 cc. of water, 
and adding 1 cc. of nitric acid, the solution should not be 
rendered turbid on adding silver nitrate solution. 

Calcium and Heavy Metals. — 

(a) The solution of 3 gm. of sodium nitrate in 50 ec. of 
water should show no change on the addition of 
hydrogen sulphide water. 

(b) The solution of 3 gm. of sodium nitrate in 50 ce. 
of water should not be changed in appearance by 
the addition of ammonia water nor by adding 
ammonium oxalate and ammonium sulphide solutions. 

Iron. — 20 ec. of the 1:20 aqueous solution, acidulated 
-with 1 ec. of hydrochloric acid, should not be reddened on 
the addition of potassium sulphocyanate solution. 

Nitrites. — Dissolve 1 gm. of sodium nitrate in 20 ce. of 
water, and add 1 cc. of dilute sulphuric acid and 1 ce. of a 
1:200 solution of metaphenylenediamine hydrochloride.* 
No yellow or yellowish-brown color should develop. 

Iodates and Nitrites. — To 5 cc. of the 1:20 aqueous solu- 
tion add 3 or 4 drops of dilute sulphuric acid and zine iodide- 
starch solution. No immediate blue color should develop. 

Potassium. — 

(a) The color imparted to the flame by sodium nitrate, 
when observed through cobalt glass, should be pure 
yellow, without violet; or at most only momentarily 
violet. 

* Should the solution of metaphenylenediamine hydrochloride have a 


color, it should be decolorized before use by warming with ignited animal 
charcoal. 


CHEMICAL REAGENTS 211 


(b) Dissolve 3 gm. of sodium nitrate with the aid of heat 
in 6 cc. of water, and to 3 cc. of the filtered solution 
add 1 or 2 drops of a solution of cobalt and sodium 
nitrite in acetic acid.* The liquid should not be- 
come turbid, and on standing two hours at about 
50° C., no yellow precipitate should form. 


SODIUM NITRITE 
NaNO2. Mol. Wt. 69.09. 


I 
SODIUM NITRITE 


White, or very slightly yellowish, tough sticks, easily and 
clearly soluble in water. The aqueous solution is slightly 
alkaline to litmus paper. The preparation contains 98 to 
99 per cent of NaNO,. 

TESTS OF PURITY 


Chlorides. — The solution of 1 gm. of sodium nitrite in 
20 ec. of water should not acquire more than a slight opa- 
lescent turbidity on the addition of 5 cc. of nitric acid and 
some silver nitrate solution. . 

Sulphates. — 20 ce. of the 1: 20 aqueous solution, acidulated 
with 5 cc. of nitric acid, should not be rendered turbid on 
the addition of barium nitrate solution. 

Potassium. — The color imparted to the flame by sodium 
nitrite, when observed through cobalt glass, should be pure 
yellow, without violet; or at most only momentarily violet. 

Heavy Metals. — 20 cc. of the 1: 20 aqueous solution should 

* The acetic acid solution of cobalt and sodium nitrite for testing for 
potassium salts is prepared as follows: 

To a solution of 10 gm. of crystallized cobalt acetate in 25 cc. of water, 
add a solution of 20 gm. of pure sodium nitrite in 40 to 50 cc. of water 


previously acidulated with a little acetic acid. Allow the solution to 
stand two hours at about 50° C., and then filter. 


212 CHEMICAL REAGENTS 


show no change on the addition of a few drops of ammonium 
sulphide solution. 

Quantitative Determination. — Dissolve 1 gm. of sodium 
nitrite in water and dilute to 100 cc. Make a mixture of 
50 ec. of decinormal potassium permanganate (accurately 
measured) with 300 cc: of water and 25 cc. of dilute sulphuric 
acid, warm to 40 or 50° C., and, while constantly shaking, 
allow the nitrite solution to run slowly into it until the red 
color disappears. Care must be taken towards the end to 
add the nitrite solution very slowly, because the change 
from red to colorless always requires some time. Not more 
than 17.6 ce. of the sodium nitrite solution should be required. 

1 cc. of decinormal KMnO, = 0.0034545 gm. of NaNO,, 
log. 53838. 

II 


SODIUM NITRITE, FREE FROM POTASSIUM 


TESTS OF PURITY 


Potassium. — To a solution of 5 gm. of crystallized cobalt 
acetate in 12 cc. of water add a solution of 10 gm. of sodium 
nitrite in 20 cc. of water previously acidulated with 2 ce. of 
diluted acetic acid. Dilute the solution with 25 ce..of water 
and allow it to stand twenty-four hours at 40 to 50°C. No 
yellow precipitate should form within this time. 

Other Tests.— The other tests and the quantitative 
determination given under Sodium Nitrite should also be 
made observing the conditions there described. 


SODIUM NITROFERRICYANIDE 
(SoprumM NiITROPRUSSIDE) 
NazFe (CN);s(NO) + 2H:O. Mol. Wt. 298.27. 


Ruby-red, transparent crystals, affording a clear solution 
with 2.5 parts of water; also soluble in alcohol. | 


CHEMICAL REAGENTS 213 : 


TEST OF PURITY 


Sulphate. — The solution of 1 gm. of sodium nitroprusside 
in 50 ee. of water acidulated with 1 ec. of hydrochloric acid 
should not be rendered turbid on adding barium chloride 
solution. | 

SODIUM OXALATE 


(SORENSEN’S OXALATE) 
NazC2Ox. Mol. Wt. 134.1. 


A white, crystalline powder, soluble in 31 parts of cold, 
and in 16 parts of boiling, water. Sodium oxalate which is 
to be used in acidimetric and oxidimetric determinations as 
a standard, is obtained by precipitation with alcohol and 
drying at 240° C. The preparation contains 100 per cent of 
Na,C,O,. 
TESTS OF PURITY 

Hygroscopic Moisture.* — 10 gm. of sodium oxalate, when 
dried in a water-drying oven for twenty-four hours, should 
not lose more than 0.001 gm. in weight. 

Sodium Carbonate, Sodium Binoxalate. — Introduce into a 
conical Jena flask about 250 cc. of water and 10 drops of 
phenolphthalein solution (0.5 gm. phenolphthalein dissolved 
in 50 ec. of alcohol and 50 cc. of water), and evaporate to 
about 180 ec. while passing in a current of pure air, free 
from carbon dioxide. Allow to cool to the ordinary tem- 
perature, add 5 gm. of sodium oxalate, shake carefully, and 
maintain the current of air. The oxalate slowly dissolves. 
If the solution is red, not more than 4 drops of decinormal 
acid should be required to render it colorless. But, if the 
solution is colorless, it must acquire a distinct red color 
on the addition of at most 2 drops of decinormal sodium 
hydroxide. 


* These tests are taken from the original paper by S. P. L. Sérensen, 
Ztschr. anal. Chem., 42, 512 (1903); J. Chem. Soc., 84, II, 684, 750 (1903). 


214 CHEMICAL REAGENTS 


Chlorides and Sulphates. — Decompose 10 gm. of sodium 
oxalate by heating in a platinum crucible, best over an 
alcohol lamp (illuminating gas contains sulphur). The car- 
bonate formed is dissolved in nitric acid, and the solution 
filtered off from the carbon. On adding silver nitrate solu- 
tion to half of the filtrate, no reaction for hydrochloric acid 
should be obtained; and in the other half no reaction for 
sulphuric acid should be obtained on adding barium nitrate 
solution. 

Iron and Potassium. — Decompose 10 gm. of sodium oxa- 
late by igniting moderately in a platinum crucible, removing 
the last traces of carbon by cautious ignition with a blast 
lamp. The residue, when treated with warm water in a 
platinum dish, should be completely soluble, and should 
leave at most a scarcely weighable trace of undissolved iron 
oxide. The solution is filtered if necessary, and supersatu- 
rated with hydrochloric acid as free from iron as possible, 
It is then evaporated in a platinum dish on the water-bath, 
and the residue dried for two hours in the drying oven at 
120° C. The residue must dissolve clear in water and the 
solution should give: 

(a) With potassium sulphocyanate solution only a very 
faint reaction for iron after boiling with a little 
nitric acid; and : 

(b) With sodium and cobalt nitrite solution, no reaction 
for potassium. 

Foreign Organic Bodies. — In a clean, thoroughly ignited 
test-tube, heat 1 gm. of sodium oxalate with 10 cc. of pure 
concentrated sulphuric acid, as long as evolution of gas 
occurs, at first gently, and then more strongly, until vapors 
of sulphuric acid begin to be evolved. When cooled, the 
color of the sulphuric acid is compared with that of another 
portion of 10 ec. of sulphuric acid similarly treated, but 
without the addition of sodium oxalate. The sodium oxalate, 


CHEMICAL REAGENTS 215 


treated in the manner described, should impart to the sul- 
phurie acid not more than an exceedingly faint brownish 
tinge. 

Quantitative Determination. — 0.4 to 0.5 gm. of the sodium 
oxalate dried to constant weight at 100° C. is cautiously 
heated in a covered platinum crucible. In order to avoid 
the error due to the sulphur in illuminating gas, the crucible 
is held in a sheet of asbestos provided with a round hole, or 
a Berzelius alcohol lamp is used. The conversion of the 
oxalate into carbonate is completed in from fifteen to thirty 
minutes; any carbon present is then burned off by more 
strongly heating the crucible while half covered. When cold, 
dissolve the contents of the crucible in water, and titrate in 
the cold with fifth normal hydrochloric acid, using methyl 
orange as the indicator. 

1 ce. of fifth normal HCl = 0.01341 gm. of Na.C,O,, log. 
12743. | 


Literature: S. P. L. Sérensen, Ztschr. anal. Chem., 36, 639 (1897); 
J. Chem. Soc., 74, II, 185 (1898). Ztschr. anal. Chem., 42, 333 (1903); 
J. Chem. Soc., 84, II, 684 (1903). Ztschr. anal. Chem., 42, 512 (1903); 
J. Chem. Soc., 84, II, 684, 750 (1903). Ztschr. anal. Chem., 44, 156 
(1905); J. Chem. Soc., 88, II, 415 (1905). 

G. Lunge, Ztschr. angew. Chem., 17, 230, 269 (1904); J. Chem. Soc., 
86, II, 289 (1904). 


SODIUM PEROXIDE 


(SopIumM SUPEROXIDE) 
NazOz. Mol. Wt. 78.10. 

A light, yellow powder, very easily soluble in water with 
the copious evolution of oxygen and great elevation of tem- 
perature. On cautiously adding sodium peroxide to a cooled, 
dilute mineral acid, hydrogen peroxide results, The prepa- 
ration contains at least 95 per cent of Na,O,. 


216 CHEMICAL REAGENTS 


TESTS OF PURITY 


Sulphates. — Add 5 gm. of sodium peroxide in small quan- 
tities at a time to a mixture of 25 cc. of hydrochloric acid 
and 100 ce. of water. The clear solution should develop no 
precipitate with barium chloride solution on standing twelve 
hours. 

Halogens. — Add 3 gm. of sodium peroxide in small quan- 
tities at a time to a mixture of 20 cc. of nitric acid and 100 cc. 
of water. The clear liquid should exhibit at most a slight 
opalescent turbidity on the addition of silver nitrate solution. 

Phosphates. — Add 2.5 gm. of sodium peroxide in small 
quantities at a time to a mixture of 20 cc. of nitric acid 
and 100 ec. of water. On now adding 25 cc. of a solution of 
ammonium molybdate in nitric acid and heating to 30 to 
40° C., no yellow precipitate should form within two hours. 

Nitrogen. — Mix 1 gm. of sodium peroxide with 0.2 gm. 
of grape sugar, very cautiously, in a capacious nickel crucible. 
Effect the deflagration of the mixture by very gently heating 
_ the bottom of the covered crucible. When cold, dissolve the 
residue in 5 cc. of water, acidulate with 10 cc. of dilute sul- 
phuric acid, and overlay a few cubic centimeters of this 
solution on 5 ec. of diphenylamine solution (see Diphenyl- 
amine). No blue color should develop at the contact-surfaces 
of the two liquids. 

Heavy Metals. — On cautiously adding 5 gm. of sodium 
peroxide to 100 cc. of water, a perfectly clear and almost 
colorless solution should result. 

40 cc. of this solution, acidulated with 10 ec. of hydrochloric 
acid, should not be affected by hydrogen sulphide water. 

AO ec. of the alkaline solution should develop no precipitate 
on the addition of a few drops of ammonium sulphide solu- 
tion, nor should the liquid acquire a brown or a green color. 

Quantitative Determination. — The quantitative determi- 


CHEMICAL REAGENTS 217 


nation of sodium peroxide is most simply effected by decom- 
posing it in a Lunge gas volumeter,* using cobalt nitrate as 
a catalyzer and measuring the volume of oxygen evolved. 

Introduce 0.5 gm. of sodium peroxide in a weighing flask 
into the outer compartment of the decomposition flask, and in 
the inner place a mixture of 15 cc. of dilute sulphuric acid and 
2 or 3 drops of a saturated solution of cobalt nitrate. On tilt- 
ing the flask, the liquid is allowed to mix with the sodium 
peroxide, whereby the decomposition of the latter is effected. 

1 cc. of O at 0° C. and 760 mm. = 0.006964 gm. of Na,0O,, 
log. 84286. 

SODIUM PHOSPHATE 
(DisoDIuM HyprocEn PHOSPHATE; SECONDARY SODIUM 
PHOSPHATE) r 
Na,HPO, + 12H,O. Mol. Wt. 358.3. 

Colorless, transparent crystals, efflorescent in dry air, and 
soluble in 6 parts of water. The aqueous solution is alkaline 
to litmus paper. 

TESTS OF PURITY 

Carbonates and Sulphates. — 20 cc. of the 1:20 aqueous 
solution should not effervesce on the addition of 1 ce. of 
hydrochloric acid; nor should it exhibit any change on the | 
subsequent addition of barium chloride solution, on standing 
three hours. : 

Chlorides. — The solution of 1 gm. of sodium phosphate 
in 20. ce. of water, acidulated with 2 cc. of nitric acid, should 
show at most a very slight opalescent turbidity on the addi- 
tion of silver nitrate solution. 

Nitrates. — To a solution of 2 gm. of sodium phosphate in 
10 ce. of water add 5 ec. of dilute sulphuric acid, 1 drop of 
1:1000 indigo solution, a granule of sodium chloride, and 


* Lunge, Chem.-Tech. Untersuch. Meth., 4 ed., 1, 158 (1904). 


218 CHEMICAL REAGENTS 


10 ce. of concentrated sulphuric acid. The blue color of the 
liquid should not disappear within ten minutes. 

Heavy Metals. — The solution of 2 gm. of sodium phosphate 
in 20 cc. of water, acidulated with 1 cc. of hydrochloric acid, 
should appear unchanged on the addition of hydrogen sulphide 
water.’ On now adding to the liquid 5 ce. of ammonia water 
and a few drops of ammonium sulphide solution, no precipi- 
tate should form, nor should a green color develop. — 

Arsenic. — Into the generating flask of a Marsh apparatus 
introduce 10 gm. of arsenic-free, metallic zine, and start the 
hydrogen with sulphuric acid (1:5). Dissolve 2 gm. of 
sodium phosphate in 50 cc. of water, introduce the solution 
in small portions at a time into the Marsh apparatus, and 
maintain a slow stream of the gas for about one hour. No 
deposit of arsenic should be visible in the reduction tube 
within this time. ; 

Potassium. — The color imparted by sodium phosphate to 
a colorless flame, when observed through cobalt glass, should 
not be tinged with violet, or should be only momentarily so. 


SODIUM PYROPHOSPHATE 


Colorless, transparent crystals, soluble in 10 to 12 parts of 
cold water, and in somewhat more than 1 part of boiling 
water, but insoluble in alcohol. The aqueous solution is 
alkaline to litmus paper. : 


TESTS OF PURITY 


Phosphates. — The 1: 20 aqueous solution of sodium pyro- 
phosphate should give a pure white precipitate with silver 
nitrate solution. 

Other tests. — The tests as given under Sodium Phosphate 
are also to be made. | 


CHEMICAL REAGENTS 219 


SODIUM SULPHATE 
NaSO, +> 10H;0. Mol. Wt. 322.32. 


Colorless, efflorescent crystals, soluble in 3 parts of cold, 
and in 0.4 part of boiling, water, but insoluble in alcohol. 
The aqueous solution is neutral to litmus paper. 


TESTS OF PURITY 


Substances Insoluble in Water. — 5 gm. of sodium sulphate 
should afford a clear solution with 50 cc. of water. 

Chlorides, Heavy Metals, Calcium, and Magnesium. — 20 cc. 
portions of the 1:20 aqueous solution should not be affected 
by hydrogen sulphide water, ammonium oxalate, silver ni- 
trate, and sodium phosphate solutions. 

Iron. — 1 gm. of sodium sulphate dissolved in 20 cc. of 
water and boiled with a few drops of nitric acid should 
remain colorless on the addition of potassium sulphocyanate 
solution. 

Arsenic. — Introduce 20 gm. of arsenic-free, metallic zine 
into the generating flask of a Marsh apparatus, and start the 
hydrogen with sulphuric acid (1:5). Dissolve 2 gm. of 
sodium sulphate in 20 ec. of water, introduce the solution in 
small portions at a time into the Marsh apparatus, and 
maintain a slow stream of gas for about half an hour. No 
deposit of arsenic should be visible in the reduction tube 
within this time. 

SODIUM SULPHIDE 
NaS + 9H2O. Mol. Wt. 240.20. 

Colorless, transparent crystals, easily and clearly soluble 
in water. The aqueous solution is alkaline to litmus paper. 
The preparation contains at least 97 per cent of Na,S + 9H,0. 


TESTS OF PURITY 


Ammonium Salts. — On dissolving 3 gm. of sodium sul- 
phide in 20 ce. of water, and heating with sodium hydroxide 


220 CHEMICAL REAGENTS 


solution, no vapors of ammonia should be evolved (to be 
ascertained by moistened litmus paper). 7 

Quantitative Determination ; Sulphites, and Thiosulphates. — 

(a) Dissolve 1 gm. of sodium sulphide in water and dilute 
to 100 ec. Allow 20 cc. of this solution to run into 
a mixture of 20 cc. of decinormal iodine and 38 cc. of 

_ hydrochloric acid which has been diluted with 100 cc. 
of water. ‘Titrate the excess of iodine with decinor- 
mal sodium thiosulphate, using starch solution as 
the indicator. 

1 ec. of decinormal I = 0.012015 gm. of NaS + 9H,0, 

log. 07972. 

(b) To 100 ce. of a solution of 1 gm. of sodium sulphide in 
sufficient water to make 100 cc., add 2 gm. of crys- 
tallized zine sulphate dissolved in 150 cc. of water; 
shake vigorously, allow to stand half an hour, and 
then filter. Titrate 50 cc. of the filtrate with deci- 
normal iodine, using starch solution as the indicator. 
Not more than 0.1 ec. of decinormal iodine should 
be required. 


SODIUM SULPHIDE SOLUTION 


Sodium sulphide solution contains 5 per cent of NaS and 
is used for determination of nitrogen according to Kjeldahl. 
TEST OF PURITY 


Nitrogen. — The test for nitrogen is to be carried out as 
described under Potassium Sulphide Solution. 


CHEMICAL REAGENTS 221 
SODIUM SULPRYITE® 


I 


SODIUM SULPHITE, CRYSTALS 
NaSO3 + 7H2O. Mol. Wt. 252.27. 

Colorless, prismatic crystals, efflorescent m air, and easily 
soluble in water. The aqueous solution is alkaline to litmus 
paper. | 

TESTS OF PURITY 

Heavy Metals and Arsenic. — The tests are carried out as 
detailed under Sodium Bisulphite. 

Quantitative Determination. — Dissolve 1 gm. of sodium 
sulphite in boiled water and dilute to 100 cc. Allow the 
solution to run from a burette into a mixture of 30 cc. of 
decinormal iodine and 5 ce. of hydrochloric acid, with con- 
stant agitation, until complete decolorization occurs. 

1 ce. of decinormal I = 0.0126136 gm. of Na,SO, + 7H,0, 
log. 10084. | 

: II 


SODIUM SULPHITE, DRIED 


A white powder, containing 85 to 90 per cent of Na,SO,. 

The tests and quantitative determination as given under 
Sodium Sulphite Crystals are to be made. 

1 ce. of decinormal I = 0.006308 gm. of Na,SO,, log. 79989. 


SODIUM THIOSULPHATE 


(SoprumM HyPosuLPHITE) 
Na.S.03; + 5H20. Mol. Wt. 248.3. 
Colorless and odorless crystals, permanent in the air at 
ordinary temperatures. Sodium thiosulphate liquefies at 
50° C. in its own water of crystallization, and is soluble in 


222 CHEMICAL REAGENTS 


less than 1 part of cold water. The 1:1 aqueous solution is 
slightly alkaline to litmus paper. 


TESTS OF PURITY 


Carbonates, Sulphates, and Sulphites. — To a solution of 
3 gm. of sodium thiosulphate in 50 cc. of water, add deci- 
normal iodine solution (about 120 ec.) until the liquid has a 
slight yellow color; on now adding barium chloride solution, 
no turbidity should ensue. 

Free Alkali. — The solution of 1 gm. of sodium thiosulphate 
in 10 ce. of water should not be reddened by phenolphthalein. 

Sulphides. — The solution of 1 gm. of sodium thiosulphate 
in 10 ec. of water should not change in appearance on the 
addition of zine sulphate solution. 

Calcium. — The solution of 1 gm. of sodium thiosulphate 
in 20 ec. of water should not be rendered turbid on the 
addition of ammonia water and ammonium oxalate solution. 

Quantitative Determination. — Dissolve 1 gm. of sodium 
thiosulphate in 100 cc. of water, and titrate with decinormal 
iodine solution, using starch solution as the indicator. 

1 cc. of decinormal I = 0.02483 gm. of Na.S,O, + 5H,0, 
log. 39498. 


SODIUM TUNGSTATE 


(Soptum WoLFRAMATE) 
Na:WO, + 2H.0. Mol. Wt. 330.13. 


Colorless prisms or rhombic plates, soluble in 4 parts of 
water. The aqueous solution is alkaline to litmus paper. 


TESTS OF PURITY 


Water. — After gently igniting 1 gm. of sodium tungstate, 
the residue should weigh 0.88 gm. 

Chlorides. — Dissolve 1 gm. of sodium tungstate in 20 ce. 
of water, add 5 cc. of nitric acid, and filter. The filtrate 


CHEMICAL REAGENTS 223 


should acquire at most a slight opalescent turbidity within 
ten minutes after adding a few drops of silver nitrate solution. 
Sulphates. — Dissolve 1 gm. of sodium tungstate in 25 ce. 
of water, add 5 cc. of nitric acid, boil for ten to fifteen minutes, 
and then filter. 20 cc. of the filtrate should not immediately 
be rendered turbid on the addition of barium nitrate solution. 
Quantitative Determination. — Dissolve 1 gm. of sodium 
tungstate in 10 ec. of water, add 10 cc. of hydrochloric acid, 
evaporate on the water-bath to dryness, and heat the residue 
for half an hour at 120° C. Treat the residue with 20 cc. of 
hydrochloric acid, and repeat the entire operation three or 
four times. Finally digest the residue with ammonium nitrate 
solution to which a little nitric acid has been added, filter, 
wash the tungstic acid with dilute nitric acid, dry, ignite, 
and weigh the residue. The latter should weigh 0.69 gm. 


SODIUM AND AMMONIUM PHOSPHATE 


(Microcosmic SALrT) 
NH.NaHPO, + 4H20. Mol. Wt. 209.19. 

Colorless, monoclinic crystals, soluble in 5 parts of water. 
The aqueous solution is alkaline to litmus paper. Sodium 
and ammonium phosphate when fused on a platinum wire 
should yield a clear and colorless bead. 


TESTS OF PURITY 


The tests given under Sodium Phosphate are to be made, 
observing the conditions there described. 


SODIUM AND POTASSIUM CARBONATE, FUSED, 
3 ANHYDROUS 


White sticks used for making carbon dioxide free from air, 
according to Kreussler. 


224 CHEMICAL REAGENTS 


THYMOL 
CoH:(CH;)(OH)(CsHz)1: 3:4. Mol. Wt. 150.11. 
Colorless, hexagonal crystals with an ethereal odor, easily 
soluble in alcohol, ether, and chloroform, but difficultly soluble 
in water (1:1100). Thymol melts at 50 to 51° C., and boils 
at 228 to 230° C. 


TESTS OF PURITY 


Inorganic Matter.— 1 gm. of thymol on ignition should 
leave no weighable residue. 

Free Acids. — Blue litmus paper should not be reddened 
by the aqueous or alcoholic solution. 

Phenol. — The 1:1100 aqueous solution may exhibit a 
milky turbidity on the addition of bromine water, but should 
show no crystalline precipitate. Nor should the solution 
afford a violet color with ferric chloride. 


TIN 
Sn. Atomic Wt. 119. 


A soft, almost silver-white metal, melting at 231° C. Tin 
dissolves in hot hydrochloric acid with the formation of 
stannous chloride. Hot concentrated nitric acid converts it 
into insoluble meta-stannic acid. 


TESTS OF PURITY 


Lead, Copper, Iron, and Zinc. — Digest 5 gm. of the tin 
with 40 cc. of nitric acid on the water-bath until the conver- 
sion of the metal into a white powder is complete. Then 
evaporate completely, stir the residue with 10 ce. of nitric 
acid and 50 ce. of water, and filter. To the filtrate add 1 ce. 
of dilute sulphuric acid, and evaporate on the water-bath as 
far as possible, and then take up the residue with 10 cc. of 
water. No weighable insoluble residue should remain (Pb). 


od CHEMICAL REAGENTS 225 


If necessary, filter, and to the filtrate add ammonia water to 
alkaline reaction. The liquid should not acquire a blue color 
(Cu). Now add ammonium sulphide solution, and allow the 
mixture to stand for four to five hours at about 50°C. Should 
any precipitate form, its weight after ignition should not 
exceed 0.002 gm. (Fe, Zn). 


TIN CHLORIDE 


(STANNOUS CHLORIDE) 
SnCl. + 2H,O. “Mol. Wt. 225.93. 


Colorless crystals, easily and completely soluble in alcohol, 
and in water acidulated with hydrochloric acid. Stannous 
chloride solution is decomposed by much water, with the 
separation of a basic stannous chloride. 


TESTS OF PURITY 


Sulphates. — Dissolve 1 gm. of stannous chloride in 5 ce. 
of hydrochloric acid (sp. gr. 1.19), and dilute with 50 ec. 
of water. The solution should not. be affected by barium 
chloride solution. 

Ammonium Compounds. — On heating 1 gm. of stannous 
chloride with 10 ec. of sodium hydroxide solution (sp. gr. 1.3), 
no vapors of ammonia should be evolved (to be ascertained 
by moist litmus paper). : 

Earths, Alkalies, and Iron. — Dissolve 2 gm. of stannous 
chloride in 10 ec. of hydrochloric acid (sp. gr. 1.19), dilute 
the solution with 100 ce. of water, and pass into the solution 
hydrogen sulphide gas until all the tin has been precipitated. 
Filter off the precipitate, evaporate the filtrate, and ignite 
the residue; the weight of the ignited residue should not 
exceed 0.001 gm. On heating the ignited residue with 1 ce. 
of hydrochloric acid, then diluting with 20 cc. of water, and 


226 CHEMICAL REAGENTS 


adding potassium sulphocyanate solution, at most only a 
slight red color should develop. 
-_ Arsenic. — Boil 2 gm. of stannous chloride with 10 ce. of 
hydrochloric acid (sp. gr. 1.19) for several minutes. The 
liquid should remain clear and colorless for one hour. 
Quantitative Determination. — Dissolve 0.5 gm. of stannous 
chloride in 2 ec. of hydrochloric acid (sp. gr. 1.19) and dilute 
the solution with 50 ce. of water. Then add 5 gm. of potas- 
sium and sodium tartrate, and sodium bicarbonate until the 
solution is alkaline to litmus paper. Now titrate with 
decinormal iodine, using starch solution as the indicator. 
1 ec. of decinormal I = 0.0112966 gm. of SnCl, + 2H,0, 
log. 05294. 


TIN CHLORIDE SOLUTION 
(STANNOUS CHLORIDE SOLUTION) 


A slightly yellow, very refractive liquid, the specific gravity 
of which should not be less than 1.90. It is obtained by 
stirring 5 parts of stannous chloride with 1 part of hydro- 
chloric acid, and then saturating the mixture with dry 
hydrochloric acid gas. 


TESTS OF PURITY 


Substances Precipitated by Alcohol. — On mixing stannous 
chloride solution with 10 times its volume of, 85 per cent 
alcohol, no turbidity should ensue on standing for one hour. 

Sulphuric Acid. —5 cc. of stannous chloride solution di- 
luted with 50 ce. of water should not be rendered turbid on . 
the addition of barium chloride solution. 


CHEMICAL REAGENTS 227 


URANIUM ACETATE, FREE FROM SODIUM 


(URANYL ACETATE) 
UO.(C2H02)2 + 2H:O. Mol. Wt. 424.58. 
A yellow, crystalline powder, easily soluble in water. As 
the preparation nearly always contains some basic salt, a 
clear solution is obtained only on adding a little acetic acid. 


TESTS OF PURITY 


Sulphates. — The solution of 1 gm. of uranium acetate in 
20 cc. of water and 2 to 3 ce. of dilute acetic acid should not 
be affected by barium chloride solution. 

Sodium. — Dissolve 5 gm. of uranium acetate in 200 cc. 
of water, with the aid of 10 cc. of dilute acetic acid. Add to 
the boiling solution an excess of ammonia water, filter, and 
evaporate the filtrate to dryness. Ignite the residue, dissolve 
it in water, and then titrate with normal hydrochloric acid, 
using methyl orange as the indicator. Not more than 0.1 ce. 
of normal hydrochloric acid should be required to produce. 
the red color. 

Earths. — The solution of 1 gm. of uranium acetate in 
20 cc. of water and 2 to 3 cc. of dilute acetic acid should 
remain clear on adding ammonia water and ammonium 
carbonate solution in excess: | 

Uranous Salt. — The solution of 1 gm. of uranium acetate 
in 20 ce. of water and 1 cc. of dilute sulphuric acid should 
be colored red on the addition of 0.1 to 0.2 ec. of decinormal 
potassium permanganate. 

Foreign Metals. — _ 

(a) On heating to boiling a solution of 5 gm. of uranium 
acetate in 100 ec. of water and 5 cc. of hydrochloric 
acid, no change should appear on passing into the 
solution hydrogen sulphide gas. 

(6) On adding to the liquid obtained under the test for 


~ 


228. CHEMICAL REAGENTS 


earths, 2 or 3 drops of ammonium su!phide solution, 
no dark-brown color should develop, nor should a 
precipitate form. 


URANIUM NITRATE 


(URANYL NITRATE) 
UO2(NOs)2 + 6H20. Mol. Wt. 502.67. 


Yellow crystals, having a greenish luster by reflected light, 
and efflorescing superficially in dry air. Uranium nitrate is 
easily soluble in water, alcohol, and ether. The aqueous 
solution is acid to litmus paper. 


_ TESTS OF PURITY 


Sulphates. — The 1:20 aqueous solution should not develop 
a turbidity within fifteen minutes on adding barium chloride 
solution. Gis 

Alkali Salts. — On igniting 1 gm. of uranium nitrate, 
treating the residue with 20 cc. of water, filtermg, and evap- 
orating the filtrate, no weighable residue should remain. 

Earths. — The solution of 1 gm. of uranium nitrate in 
20 ce. of water should remain clear on the addition of ammonia 
water and ammonium carbonate solution in excess. 

Uranous Salt. — The solution of 1 gm. of uranium nitrate 
in 20 ec. of water and 1 cc. of dilute sulphuric acid should 
be colored red on the addition of 0.1 to 0.2 cc. of decinormal 
potassium permanganate. 

Foreign Metals. — 

(a) The liquid obtained under the test for earths, when 
treated with 2 or 3 drops of ammonium sulphide 
solution, should not acquire a dark-brown color, nor 
should it develop a precipitate. 

(b) On heating to boiling a solution of 5 gm. of uranium 
nitrate in 100 cc. of water and 5 ec. of hydrochloric 


CHEMICAL REAGENTS 229 


acid, no change should appear on passing hydrogen 
sulphide gas into the solution. 


WATER DISTILLED 
H.0. Mol. Wt. 18.01. 


Distilled water must be neutral to litmus paper. 


TESTS OF PURITY . 


Ammonia and Ammonium Compounds. — 50 cc. of the 
water should show no change on the addition of 10 to 15 
drops of Nessler’s reagent. | 

Chlorides. — 100 cc. of the water should show no change 
on adding a few drops of nitric acid followed by silver nitrate 
solution. 

Sulphates. — On adding 0.25 ec. of hydrochloric acid and 
some barium chloride solution to 100 cc. of water, no precipi- 
tate of barium sulphate should form on standing twelve 
hours. 

Nitrates. — Introduce 5 cc. of diphenylamine solution (see 
Diphenylamine) into a test tube, and overlay it with 10 ce. 
of water. No blue color should form at the contact-surfaces 
of the two liquids. 

Non-volatile Matter. — 100 cc. of the water evaporated on 
the water-bath should leave no weighable residue. 

Heavy Metals and Calcium. — 100 cc. of the water should 
show no change with hydrogen sulphide water, ammonia 
water, ammonium sulphide, and ammonium oxalate solutions. 

Substances Oxidizable by Permanganate (Organic Matter, 
Nitrites, etc.). — Heat to boiling 100 cc. of the water with 
1 cc. of 16 per cent sulphuric acid, add 1 drop of potassium 
permanganate solution (1:1000), and maintain the boiling 
_ for three minutes. The liquid should not: be decolorized. 


230 CHEMICAL REAGENTS 


XYLIDINE 


A yellow to yellowish-brown liquid, having a specific 
gravity of 0.981 to 0.984, and boiling at 212 to 215° C. 


TEST OF PURITY 


Substances Insoluble in Hydrochloric Acid.—10 cc. of 
xylidine should afford a perfectly clear solution with-a mix- 
ture of 10 ec. of hydrochloric acid and 10 cc. of water. 


ZINC 
Zn. Atomic Wt. 65.4. 
A shining, white metal, exhibiting a slight, bluish-gray 
luster, and occurring on the market in various forms. 


I 


ZINC, FREE FROM ARSENIC,. SULPHUR, PHOS- 
PHORUS, AND IRON 


This grade of zine occurs in three forms, — granulated, 
thin sticks, and thick sticks. | 


TESTS OF PURITY 


Arsenic. — Introduce 20 gm. of zine into the generating | 
flask of a Marsh apparatus, and start the hydrogen with 
arsenic-free, dilute sulphuric acid (1:5), maintaining the 
flow of gas until.the metal is almost completely dissolved. 
At the end of the test, no deposit of arsenic should be visible 
within the reduction tube. 

Matter Oxidizable by Potassium Permanganate. — Dissolve 
10 gm. of zinc in a mixture of 60 cc. of water and 15 cc. of 
pure sulphuric acid (sp. gr. 1.84) in a flask provided with a 
rubber valve; no black flocks should remain undissolved. 


CHEMICAL REAGENTS | 231 


As soon as the zinc has dissolved, add to the solution, drop 
by drop, decinormal potassium permanganate. Not more 
than 0.1 cc. should be required to produce a distinct pink 
color. Should more of the permanganate solution be required, 
the dilute sulphuric acid (15 cc. of sulphuric acid and 60 ee. 
of water) should be titrated for the purpose of control, without 
zinc, using the same solution of decinormal potassium 
permanganate. 

Compounds of Sulphur, Phosphorus, etc. — Into a narrow 
test-tube introduce 1 gm. of zine together with 5 to 10 ce. of 
dilute, arsenic-free sulphuric acid, and in the upper part of 
the tube insert a plug of cotton, which serves to hold back 
the water carried off by the escaping hydrogen. Over the 
mouth of the tube lay a small piece of filter paper which has 
been moistened with a 1:1 silver nitrate solution, and care- 
fully dried. The reaction is allowed to proceed in a dark 
place which is perfectly free from hydrogen sulphide. On 
standing two -hours, the silver nitrate paper should show 
neither a yellow nor a black color. 


Ths: 


ZINC, FREE FROM ARSENIC, NEARLY FREE FROM 
IRON 


This grade of zinc is in various forms, — granulated, thick 
sticks, thin sticks, sheets. 


TESTS OF PURITY 


Arsenic. — Introduce 20 gm. of zinc into the generating 
flask of a Marsh apparatus, and start the hydrogen with 
arsenic-free, dilute sulphuric acid (1:5), maintaining the flow 
of gas until the metal is completely dissolved. At the end 
of the test no deposit of arsenic should be visible within the 
reduction tube. 


232 CHEMICAL REAGENTS 


Matter Oxidizable by Permanganate. — Dissolve 10 gm. of 
zinc in a mixture of 60 ec. of water and 15 cc. of pure con- 
centrated sulphuric acid in a flask provided with a rubber 
valve. The solution should contain only a very slight quan- 
tity of undissolved black flocks. As soon as the zinc has 
dissolved, add to the solution, drop by drop, normal potassium 
permanganate. Not more than 0.1 cc. should be required 
to produce a distinct pink color. 

This grade of zine in powder form should, in addition to 
the above, be tested as follows: 

Chlorides. — Dissolve 5 gm. of the zine in a mixture of 
50 ec. of nitric acid and 100 cc. of water. This solution 
should not show more than a slight opalescent turbidity on 
the addition of silver nitrate solution. 


IIT 
ZINC, FREE FROM ARSENIC 
This zine is used in the following forms: Granulated, thick 


sticks, thin sticks. 


TEST OF PURITY 


Arsenic. — Introduce 20 gm. of zine into the generating 
flask of a Marsh apparatus, and start the hydrogen with 
arsenic-free, dilute sulphuric acid (1:5), maintaining the flow 
of gas until the metal is almost completely dissolved. At 
the end of the reaction, no deposit of arsenic should be visible 
within the reduction tube. 


IV 
ZINC DUST 


A fine, gray powder, containing about 90 per cent of 
metallic zine. 


CHEMICAL REAGENTS 233 


TESTS OF PURITY 


Nitrogen (from Nitrates and Ammonia). — Dissolve 10 gm. 
of zinc dust in a mixture of 20 cc. of sulphuric acid (sp. gr. 
1.84) and 200 cc. of water. Add to the solution 100 cc. 
of sodium hydroxide solution I, distil off about 50 ec., and 
collect the distillate in a receiver containing about 20 cc. of 
water and 2 to 3 cc. of decinormal hydrochloric acid. Titrate 
the distillate with decinormal potassium hydroxide, using 
methyl orange as the indicator. Not more than 0.2 ce. of 
the acid should have been consumed by the ammonia. 

Determining the Value of Zinc Dust. — Introduce 1 gm. of 
zinc dust together with a few glass beads into a flask of 
about 200 cc. capacity, closed with a glass stopper, and then 
add a mixture of 30 cc. of potassium iodate solution and 100 
ec. of sodium hydroxide solution (potassium iodate solution: 
15.25 gm. KIO, to 300 ec. H,O; sodium hydroxide solution: 
300 gm. NaOH to 1000 ec. H,O). Now shake the contents 
of the flask vigorously for five minutes: transfer, without 
filtering, to a graduated flask of 1000 cc. capacity; fill up to 
the mark and mix. Of this solution transfer 100 cc. into an 
iodine distillation apparatus. Add 50 ce. of dilute sulphuric 
acid, and after expelling the air by means of carbon dioxide, 
distil, and receive the iodine in potassium iodide solution 
(1:5). The distillation is ordinarily complete in about 
twenty minutes, and may be recognized by the contents of 
the retort having become colorless. The iodine distilled over 
is titrated with decinormal sodium thiosulphate. 

61° = 15.2n* 

1 cc. of decinormal Na.S,O, = 0.01635 gm. of Zn, log. 21352. 

* 15 Zn + 30 NaOH = 15 Zn(ONa), + 15 H,. 


5KIO, + 15H, = 5KI + 15H,0. 
KIO, + 5 KI + 3H,S0, = 3K,S0, + 3H,0 + 61. 


234 CHEMICAL REAGENTS 


ZINC CHLORIDE 
ZnCl. Mol. Wt. 136.3. 


A dry, white powder, deliquescent in the air, and easily 
soluble in water and in alcohol. The aqueous solution is 
acid to litmus paper. 


TESTS OF PURITY 


Solubility (Basic Zinc Chloride). — The solution of 1 gm. 
of zine chloride in 1 cc. of water should be clear, or at most 
only slightly turbid; any turbidity caused in the solution by 
the addition of 3 ec. of alcohol should disappear on the 
addition of 1 drop of hydrochloric acid. 

Sulphates. — 10 cc. of the 1: 10 aqueous solution acidulated 
with a few drops of hydrochloric acid should not be rendered 
turbid by barium chloride solution. 

Foreign Metals and Alkalies. — 

(a) The solution of 1 gm. of zine chloride in 10 cc of 
water acidulated with 1 ec. of hydrochloric acid 
should appear unchanged after the addition of 
hydrogen sulphide water. 

(6b) 1 gm. of zine chloride should afford a clear solution 
with 10 cc. of water and 10 cc. of ammonia water. 
On adding hydrogen sulphide water to the solution, 
a pure white precipitate should form. On filtering, 
evaporating the filtrate to dryness, and igniting, no 
weighable residue should remain. 


ZINC IODIDE-STARCH SOLUTION 


A colorless, clear, or only slightly opalescent liquid. It 
deteriorates with age, acquiring a blue color. 


TESTS OF SENSITIVENESS 


A mixture of 1 cc. of zine iodide-starch solution and 20 cc. 


CHEMICAL REAGENTS : 235 


of water should acquire an intense blue color on adding 
1 drop of decinormal iodine solution. | 
Zine iodide-starch solution diluted with 50 volumes of 
water should not acquire a blue color on the addition of 
dilute sulphuric acid. 
ZINC OXIDE 
ZnO. Mol. Wt. 81.4. 


A white, amorphous powder, having a faint yellowish 
tinge. Zinc oxide is insoluble in water, but is soluble in 
dilute acetic acid and in mineral acids. 


TESTS OF PURITY 


Arsenic. — A mixture of 1 gm. of zine. oxide and 3 cc. of 
stannous chloride solution should not acquire a darker color 
on standing one hour. 

Sulphates and Chlorides. — On shaking 2 gm. of zine oxide 
with 20 cc. of water and filtering, the acidulated filtrate 
should show no reaction on the addition of barium nitrate 
solution, and should acquire at most a slight opalescent 
turbidity on the addition of silver nitrate solution. 

Carbonates, Calcium, Magnesium, and Foreign Heavy 
Metals. — 1 gm. of zine oxide should dissolve completely in 
10 cc. of dilute acetic acid without effervescence. On adding 
to this solution 20 cc. of ammonia water, a clear colorless 
liquid should result which should not show a change on the 
addition of ammonium oxalate and sodium phosphate solu- 
tions, and which should give a pure white precipitate with 
hydrogen sulphide gas. 3 

Foreign Bodies which Reduce Permanganate when Zinc 
Oxide is Dissolved in Dilute Sulphuric Acid. — Very carefully 
triturate 3 gm. of zine oxide in a mortar with 20 ce. of water 
containing in solution 0.2 gm. of pure ferric alum free from’ 
ferrous salt. Then add to the mixture 25 ec. of diluted 
sulphuric acid, and effect complete solution by gently heating. 


236 CHEMICAL REAGENTS 


Dilute the solution with 100 cc. of thoroughly boiled and 
cooled water, and add decinormal potassium permanganate. 

A single drop of the permanganate should suffice to impart 
a distinct pink color to the solution. 


ZINC SULPHATE 
ZnSO. + 7H:0. Mol. Wt. 287.57. 


Colorless crystals, slowly efflorescent in dry air, soluble in 
0.6 part of water, and insoluble in alcohol. The aqueous 
solution is acid to litmus paper. 


TESTS OF PURITY 


Chlorides. — The 1:20 aqueous solution should not be 
affected by silver nitrate solution. 

Foreign Metals. — A solution of 0.5 gm. of zine sulphate in 
10 cc. of water and 5 cc. of ammonia water should be clear 
and should afford a pure white precipitate with hydrogen 
sulphide water. 

Iron. — 1 gm. of zinc sulphate dissolved in 20 cc. of water 
acidulated with a few drops of nitric acid and boiled should 
not be reddened by potassium sulphocyanate solution. 

Nitrates. — On adding to 5 cc. of a 1:10 zine sulphate 
solution 1.drop of indigo solution and 5 ec. of concentrated 
sulphuric acid, the blue color should not disappear. 

Ammonium Compounds. — On heating 1 gm. of zine sul- 
phate with sodium hydroxide solution, no vapors of ammonia 
should be evolved (to be ascertained by moist litmus paper). 

Free Sulphuric Acid. — On shaking 2 gm. of zine sulphate 
with 10 cc. of 85 per cent alcohol and, after ten minutes, 
filtering, the filtrate, when diluted with 10 cc. of water, 
should not redden blue litmus paper. 

Arsenic. — Introduce 20 gm. of arsenic-free, metallic zinc 


CHEMICAL REAGENTS 237 


into the generating flask of a Marsh apparatus, and start the 
hydrogen with dilute (1:5) sulphuric acid. Dissolve 2 gm. 
of zine sulphate in 20 cc. of water, introduce the solution in 
small quantities at a time into the Marsh apparatus, and 
maintain a slow stream of gas for about half an hour. At 
the end of this period no deposit of arsenic should be visible 
within the reduction tube. 


238 


CHEMICAL REAGENTS 


INTERNATIONAL ATOMIC WEIGHTS, 1906 
















































Aluminum. .|Al | 27.1 ||Hydrogen ....|H 1.008{Rubidium.. Rb{ 85.5 
Antimony ...|Sb |120.2 |Indium....... In {115 Ruthenium |Ru |101.7 
Argon .....;:; A | 39.9 (lodine ....... I |126.97 |Samarium .|/Sm/|150.3 
Arsenic .|As | 75.0 |Iridium ...... Ir {193.0 |Scandium .|Se | 44.1 
Barium , |Ba 137.4 rom... 2.6... Fe| 55.9 |Selenium..|Se | 79.2 
Bismuth ...|Bi |208.5 |IKrypton ..... Kr} 81.8 |Silicon.....|Si | 28.4 
Boron .. ... B 11 |/Lanthanum ...|/La|138.9  |ilver.....|/Ag |107.93 
Bromine ...|Br| 79.96|Lead......... Pb /206.9 |Sodium ...|Na/} 23.05 
Cadmium ...|Cd |112.4 Lithium ...... Li | 7.03 {Strontium .|Sr | 87.6 
Cesium .|Cs |132.9 Magnesium... .|Mg| 24.36 |Sulphur...|S | 32.06 
Calcium ..../Ca| 40.1 Manganese... .|Mn} 55.0 Tantalum .|Ta |183 
Carbon .{C | 12.0 |!Mercury...... Hg/200.0 {Tellurium .|Te |127.6 
Cerium .|Ce |140.25|Molybdenum. .|/Mo| 96.0 |[Terbium . . |Tb |160 
Chlorine .../Cl | 35.45/Neodymium...|Nd/143.6 |[Fhallium. .|T1 |204.1 
Chromium. .|Cr | 52.1 |INeon ........ Ne| 20 |Thorium ..|Th |232.5 
Cobalt .....|Co| 59.0 |iINickel ....... Ni} 58.7 |Thulium ..|Tm/)171 
Columbium .|Cb| 94 ||Nitrogen ..... N | 14.04 |Tin....... Sn /|119.0 
Copper ....|Cu| 63.6 |Osmium...... Os} 191 |Titanium .|Ti |48.1 
Erbium ....|Er| 166 |(Oxygen....... O | 16.00 |Tungsten .|W /|184 
Fluorine ... .|F 19 |/Palladium .|Pd |106.5 ranium...|U |238.5 
Gadolinium ./Gd| 156 ||Phosphorus....|P | 31.0 |/Vanadium.|/V | 51.2 
Gallium ....|Ga| 70 ||Platinum .|Pt |194.8 enon ....|/Xe |128 
Germanium..|Ge | 72.5 ||Potassium K | 39.15 |Ytterbium.| Yb |173.0 
Glucinum...|Gl | 9.1¢|/Praseodymium |Pr |140.5  |/Yttrium ../Yt | 89.0 
Gold .|Au|197.2 ||Radium...... Rd| 225 MIC Gh) Zn | 65.4 
Helium..... He} 4 |}Rhodium Rh/103.0 Zirconium .|Zr | 90.6 
1 CC. OF NORMAL HYDROCHLORIC ACID IS THE EQUIVALENT OF: 
Gram. Log. 
birninia Whee NET s os). cs... fcc cc catu ct ke ee ess 0.01706 | 23198 
Barium Hydroxide Ba(OH)2+8 H20 ................. 0.15777 | 19802 
Calcium Hydroxide Ca(OH): ............... eee ee eens 0.03705 | 56879 
Potassium Bicarbonate KHCOs....................... 0.10015 | 00065 
Potassium Carbonate K.COs 2.050.000. cece ec een es 0.06915 | 83979 
Potassium Ty dtoxide BU eso. ae isn os eee 0.5615 74935 
Sodium Bicarbonate NaHCQ3......................56- 0.08405 | 92454 
Sodium Borate, Anhydrous* Na2B,O;7 ................ 0.10105 | 00453 
Sodium Borate, Cryst.* Na2B,0O7+ 10 H2O............ 0.19113 | 28132 
Sodium Carbonate, Anhydrous Na:CO;3............. 0.05305 | 72469 
Sodium Carbonate, Cryst. NacCO;+10H20......... 0.14313 | 15573 
Sodium Hydroxide POWER Si xe och pas Sear ues 0.04005 | 60260 














* Indicator: Methyl Orange. 


CHEMICAL REAGENTS 


239 


1 CC. OF DECINORMAL POTASSIUM PERMANGANATE SOLUTION IS THE 


EQUIVALENT OF: 











Gram. Log. 
Acid Oxalic, Anhydrous H:C2O,................... 0.0045008] 65329 
Acid Oxalic, Cryst. H.C.0,+ 2H2O.........:...... 0.0063024| 79951 
Ammonium Oxalate (NH,)2C204 + H2O............ 0.007108 | 85175_ 
Heycrogen Feroxwie Tye sol sees eae clas owe es 0.0017008] 23065 
Indigotin (Indigo Blue) CizHioN2O2 ............... 0.007415 | 87011 
LE ee a eicc sy siKd Malai caer alsa aie ates ee 0.00559 74741 
Iron Sulphate, Ferrous FeSO. + 7H2O............. 0.027807 | 44415 
Iron and Ammonium Sulphate FeSO.(NH,)SO. + 
PRB alr ee Oe ail oy dag vs cele oF ae lmawigaiy’ b owl eis 0.039226 | 59358 
Potasenmms Nitrite INO}. ois eee lege edd oes o's 0.0042595| 62936 
Potassium Oxalate, Neutral K;C.0,+ HO ......... 0.0092158} 96453 
Potassium Tetraoxalate KHC.O, + H.C:0.-+ 2 H.0. .|0.006355 | 80312 
BiVOr NIRTHO AEN! i idee cee. bebe ele hae 0.0076985| 88640 
CRIN. PIICEEOR INBIN 0s sink ougreccdle he cee maure dee 0.0034545| 53838 
Sodium Oxalate Nase i: 6 6. eee eicalelerearercee es 0.006705 | 82640 














1 CC. OF NORMAL POTASSIUM HYDROXIDE SOLUTION IS THE 


EQUIVALENT OF: 











Gram. Log. 

PeOHE RMI: SE eR 5 85 ec bse aig Hod doe wake a's wasn as 0.06003 | 77837 
Acid Acetic Anhydride (CH3-CO).Q................ 0.051024) 70777 
Acid Citric CeHs0; + HO .................... **..| 0.07002 | 84522 
PRE REIN OIE igo orice cogent Sicah sty Aadehessping wvauhe dae, 0.12797 | 10710 
PACA, EUV CSOT EA DSR 3 so soe caitlin ek S orelpe-slons seeeai 0.08096 | 90827 
PORE TEV ICRIORIO BE oa sck ase aig ccastlaraddowaac ute whats 0.036458} 56179 
Pied FE CPOR Ore TEE ose are& ope: cugigy drsvarace abe and 0.020 30103 
PA TNR T TO ERO i os ce eh mceees, c eodin a puearatbotials Biecorats 0.06304 | 79962 
Acid Oxalic, Cryst. H,C.0,+ 2H20........ epee 0.063024} 79950 
Acid Oxalic, Sublimed H;C,0, ........ erty ees 0.045008} 65329 
Acid Phosphoric PERE OE nad oss ee ene Sa 0.09802 | 99131 
Aord PRoemnonio tT! By POG 0 nie SR RE 0.04901 | 69028 
Acid Sucemin Giliade os o.oo as oe earls es ea 9.05902 | 77100 
Acid Sulphur Passe cc kis ee ee a eee 0.049038} 69053 ~ 
Acid Sulphuric Anhydride SO3...............+..5. 0.04003 | 60239 
Acid Tartaric CsH¢ TsO SERN EES pgibtactaeyt ar ey rH eI 0.07502 | 87518 
Hydroxylamine Hydrochloride } NH2OH:HCL...... 0.06952 | 84211 
Potassium Bisulphate KHSO, .................... 0.13621 13421 

0.13813 | 14029 


Sodium Bisulphate NaHSQu:.........-........0... 














* Indicator: Methyl Orange. 


+ Indicator : Phenolphthalein. 


240 CHEMICAL REAGENTS 


1 CC. OF DECINORMAL SODIUM THIOSULPHATE sins ic gana IS THE 


EQUIVALENT OF : 











Gram. Log. 
Ag POGIG Ae es ee ee eh ee ee 0.002933 46731 
Acid Todic Aniydride Is0; 42... .. 2. So ee 0.0027828 | 44448 
Barium Persie PO ei SR a a Pe 0.00847 92788 
Peron ee er a ae, te i eo eed 0.007996 90287 
TPO eee ee ka ee ee 0.003545 54962 
Chiron 1 aOsine Ors... ok oe ck ele an 0.003336 52323 
Hydrogen’ Peroxide: HiOs. 0.5... js oe ee .../0.0017008 | 23065 
OG Be i ee ema sg Se ee ge Te 0.012697 10369 
Ba PS SRG STL Ee Oe es atte ik Pleas 5 eae i ReaD 0.00559 74741 
Potassium Biniodate KIO3;-HIO;.................. 0.00325082|} 51199 
Poapasiim Bromate 1 BrOe oo. ic. Bee 0.00278516| 44485 
Potassium Chromate K:CrO,...... eee ae aie be a 0.00648 81158 
Potassium Dichromate K.Cr.O7 ................0.. 0.0049083 | 69092 
RrAMPMPMAYSTNY ACHR AS Pe ic ee does bev wk ee ke 0.0035686 | 55250 
Sodium Bromate NaBbrOs «60 oso. ss oe ec eck eee 0.002517 40089 














— 


1 CC. OF DECINORMAL IODINE SOLUTION IS THE EQUIVALENT OF : 











Gram. Log. 
Are PEPONGUG ABIDES ES bee dda n't ba8 0.00495 69461 
Psi Pete TAR OE PRN oo SS sik pied nn es oo ees 0.003203 | 50556 
RPM TIAA DOIN G05 eins olga! 63 6 ok ls aa ho Dee oO 0.004398 | 64326 
Potassium Bisulphite KHSO;..................... 0.0060105| 77887 
Sodium Bisulphite NaHSO;...................... 0.0052059| 71649 
Sodium Sulphide NaS +9H.O ................... 0.0120152} 07972 
Sodium Sulphite, Cryst. Na2SO3;+ 7H2O ........... 0.0126136} 10084 
Sodium Su phite, Anhydrous NaSO3 ............. 0.006308 | 79989 
Sodium Thiosulphate NaS.03;+ 5H.O............. 0.02483 39498 
Stannous Chloride SnCl.+ 2H.O.................. 0.0112966| 05294 














CHEMICAL REAGENTS 


241 


1 CC. OF FIFTH-NORMAL HYDROCHLORIC ACID IS THE EQUIVALENT OF: 











Gram. Log. 
Sodium Borate Cryst.* Na2B,O7 + 10H20.......... 0.038226 | 58235 
Sodium Borate, Anhydrous *Na2B,O7.............. 0.02021 30557 
Sodium Oxalate (after ignition) NazC.O............. 0.01341 12743 














* Indicator : Methyl Orange. 


1 CC. OF FIFTH-NORMAL POTASSIUM HYDROXIDE SOLUTION IS THE 


EQUIVALENT OF : 











_ Gram. Log. 
Acid Oxalic, Cryst. H-C20. + SED os OS eee Rea 0.012605 10055 
Acid Oxalic, Anhydrous HO, ........2.....005- 0.009001 | 95432 
Potassium Biniodate * KIO3;-HIO;3 .............-.. 0.078018 | 89219 
Potassium Tetraoxalate *KHC.O, + H,C.0.+2H.0. .|0.016947 | 22909 














* Indicator: Phenolphthalein. 


ae 
de - 
ae 





INDEX 


Acetone, 1. 
Acetic Acid, 2, 3, 4, 5. 


Anhydride, 5. 


Acid Acetic, 2, 3, 4, 5. 


Anhydride, 5. 
Diluted, 30 per cent, 4. 
Glacial, 96 per cent, 3. 
36 per cent, 4. 
90 per cent, 4. 
994 per cent, 2. 
Alphanaphthylaminesulphonic, 
20. 
Arsenous, 65. 
Arsenous Anhydride, 65. 
Boric Anhydride, 5. 
Fused, 5. 
Carminic, 6. 
Chlorplatinic, 149. 
Chromic Anhydride, 92. 
Citric, 7. 
Fluosilicic, 16. 
Gallic, 8. 
Hydriodie, 9, 10. 

Sp. Gr. 1.5, 9. 

Sp. Gr. 1.7, 10. 
Hydrobromice, 10. 
Hydrochloric, 12, 14, 15. See 

Preliminary 
Note. 
Concentrated, 
12. 
Diluted, 14. 
Fuming, 12. 
Sp. Gr. 1.050, 15. 
Sp. Gr. 1.124, 14. 


e 





Acid Hydrochloric Sp. Gr. 1.19, 12. 
Hydrofluoric, 15. 
Hydrosilicofluoric, 16. 

Iodic, 17. 
Anhydride, 18. 
Molybdic, 18. 
Anhydride, 18. 
100 per cent, 18. 
Naphthionic, 20. 
Naphthylaminesulphonic, 20. 
Nitric, 20, 21, 22. See Pre- 
liminary Note. 
Crude, 22. 
Fuming, 22. 
Sp. Gr. 1.40, 20. 
Sp. Gr. 1.20, 22. 
Sp. Gr. 1.30, 21. 
Sp. Gr. 1.153, 22. 
Oxalic, 23. 
Sublimed, 25. 
Perchloric, 25. 
Phosphomolybdic, 26. 
Phosphoric, 26, 28, 29. 
Anhydride, 29. 
Sp. Gr. 1.12, 28. 
Sp. Gr. 1.057, 29. 
Sp. Gr. 1.7, 26. 
Glacial, 29. 
Ortho, 26, 28, 29. 
Meta, 29. 

Phosphotungstic, 30. 

Picric, 31. 

Picronitric, 31. 

Pyrogallic, 185. 

Rosolic, 32. 


243 


244 


INDEX 


Acid Silicofluoric, 16. 


Succinic, 33. 

Sulphanilic, 34. 

Sulphuric, 34, 36, 37.. 
Anhydride, 37. 
Concentrated, 34. 
Diluted, 16 per cent, 

36. 
Fuming, 38, 39. 
Fuming, Free from 
Nitrogen, 38. 
Fuming, with Phos- 
phoric Anhydride, 
41. 
Sp. Gr. 1.84, 34. 
with Phosphoric 
Anhydride, 40. 
10 per cent, 37. 

Sulphurous, 41. 

Cubes for Gener- 
ating, 42. 

Tannie, 42. 

Tartaric, 43. 

Thioacetic, 44. 


Alcohol, 44, 46. 


Absolute, 44. 

85 per cent, 46. 

95 per cent, 46. 

Amyl, for Gerber’s Fat De- 
termination, 47. 

Amylic, 47. 

Ethylic, 44, 46. 

Methylic, 48. 


. Alphanaphthol, 49. 
Aluminum Oxide, 49. 
Ammonia Water, 50, 51, 52. See 


Preliminary Note. 
Concentrated, 51. 
Stronger, 50. 

10 per cent, 52. 
20 per cent, 51. 
28 per cent, 50. 


Ammonio-Cupric Chloride, 99. 
Ammonio-Ferric Alum, 122. 





Ammonium Acetate, 53. 
Carbonate, 53. 
Chloride, 54. 
Citrate Solution, 55. 
Dithiocarbonate Solution, 56. 
Fluoride, 56. 
Molybdate, 57. 
Nitrate, 58. 
Oxalate, 59. 
Phosphate, 59. 
Sulphate, 61. 
Sulphide Solution, 62. 
Sulphocyanate, 61. 
Sulphydrate Solution, 62. 
Thioacetate Solution, 63. 
Thiocyanate, 61. 
Amy] Alcohol, 47. 
for Gerber’s Fat De- 
termination,-47. 
Aniline, 63. 
Animal Charcoal, 89. 
Antimonous Oxide, 64. 
Antimony Oxide, 64. 
Trioxide, 64. 
Apparatus, Marsh. See Preliminary 
Note. 
Arsenic Trioxide, 65. 
Arsenous Anhydride, 65. 
Atomic Weights, 238. See Prelimi- 
nary Note. 
Azolitmin, 66. 


Barium Acetate, 66. 
Carbonate, 67. 
Chloride, 68. 
Dioxide, 69. 
Hydrate, 70. 
Hydroxide, 70. 

Solution, 71. 
Nitrate, 71. 
Peroxide, 69. 
Sulphide, 72. 
Superoxide, 69. 
Baryta Water, 71. 


INDEX 


Benzene, 72. 
Benzidine, 73. 
Benzin, 74. 
Petroleum, 74. 
Benzol, 72. 
Bismuth Nitrate, Basic, 74. 
Subnitrate, 74. 
Blood Charcoal, 89. 
Borax, 198, 194, 195, 196. 
Anhydrous, 196. 
Glass, 196. 
Boric Anhydride, 5. 
Boron Trioxide, 5. 
Bromine, 76. 
Water, 77. 
Brucine, 77. 


Cadmium and Potassium Iodide, 78. 
Borotungstate Solution, 
78. 

Calcium Biphosphate, 85. 
Carbonate Precipitated, 79, 
Chloride, Crystals, 80. 

Dry Granulated, 81. 
Fused, 82. 
Hydroxide, 82. 
Solution, 131. 
Oxide, from Iceland Spar, 82. 
Marble, 83. 
Phosphate, Acid, 85. 
Dibasic, 84. 
Monobasic, 85. 
Primary, 85. 
Secondary, 84. 
Super, 85. 
Tertiary, 86. 
Tribasic, 86. 
Sulphate, 86. 
Sulphide, 87. 
Carbon Disulphide, 87. 
Carmine, 88. 
I (Naccarat), 88. 

Caustic Potash, 167, 168, 170, 171. 

Soda, 202, 204, 205. 


- 





245 


Caustic Soda Solutions, 207. 
Charcoal, Animal, 89. 
Blood, 89. 
Chlorinated Lime, 130. 
Chlorine Water, 90. 
Chloroform, 91. 
Chromic Anhydride, 92. 
Chromium Trioxide, 92. 
Cobalt Nitrate, 93. 
Cobaltous Nitrate, 93. 
Collodion, 94. 
Concentrated Hydrochloric Acid, 
12. 
Sulphuric Acid, 34- 
Copper and Ammonium Chloride, 
99. 
by Electrolysis, 94. 
Chloride, Cupric, 96. 
Cuprous, 97. 
Dichloride, 96. 
Monochloride, 97. 
Oxide, 97. 
Sulphate, 98. 
Corallin, 32. 
Corrosive Sublimate, 140. - 
Cubes for Generating Sulphurous 
Acid, 42. 
Cupric Chloride, 96. 
Oxide, 97. 
Sulphate, 98. 
Cuprous Chloride, 97. 


Dibasic Calcium Phosphate, 84. 
Dicalcium Phosphate, 84. 
Diphenylamine, 100. 

Disodium Hydrogen Phosphate, 217. 


Distilled Water, 229. 


Ether, 101, 102. 
Anhydrous, Distilled over So- 
dium, 102. 
Sp. Gr. 0.720, 101. 
Petrolic, 74. 
Ethyl] Alcohol, 44, 46. 


246 
Ethyl Ether, 101, 102. 


Ferric Ammonium Sulphate, 122.. 
Chloride, 118. 


Ferrous Ammonium Sulphate, 123. 


Chloride, 119. 

Sulphate, 120. 

Sulphide, 121. 
Fuming Sulphuric Acid, 38, 39. 
Furfural, 102. 
Furfurol, 102. 


Gallein, 103. 
Liquid, 103. 
Glycerin 103, 104. 
Sp. Gr. 1.250, 103. 
Sp. Gr. 1.23, 104. 
Glycerol, 103, 104. 
Guaiacin, according to Schmitt, 105. 
Gypsum, 86. 


Hematein, 105. 
Hematoxylin, 106. 
Hide Powder, 106. 
Hydriodie Acid, 9, 10. 
Hydrochloric Acid, 12,14, 15. See 
Preliminary Note. 
Hydrogen Dioxide, 107. 
Peroxide, 30 per cent, 107. 
Sulphide Water, 109. 
Hydroxylamine Hydrochloride, 109. 


Indigo, 110, 111. 
Blue, 111. 
Synthetic, 110. 

Vegetable, 111. 

Indigotin, 111. 

Iodeosin, 112. 

Iodic Anhydride, 18. 

Iodine, 113. 
Pentoxide, 18. 
Resublimed, 113. 
Water, 114. 

Iron, 114, 115, 117. 





INDEX 


Iron and Ammonium Sulphate, Fer- 
ric, 122. 
and Ammonium Sulphate, Fer- 
rous, 123. 
by Hydrogen, 115. 
Chloride, Ferric, 118. 
Ferric, Solution, 119. 
Ferrous, 119. 
Powder, 117. 
Reduced, 115. 
Sulphate, Ferrous, 120. 
Sulphide, 121. 
Wire, 114. 


Kassner’s Mixture, 143. 


Lacmoid, 124. 
Lead Acetate, 125. 
Chromate, 126. 
Dioxide, 126, 128. 
Oxide, Brown, 126, 128. 
Brown, Free from Man- 
ganese, 126. 
Brown, for Dennstedt’s 
Analysis, 128. 
Yellow, 129. 
Peroxide, 126, 128. 
Subacetate Solution, 130. 
Superoxide, 126, 128. 
Lime, 83. 
Chlorinated, 130. 
Slaked, 82. 
Sulphurated, 87. 
Water, 131. 
Litharge, 129. 
Litmus, 131. 


- Magnesia, 134, 136. 


Magnesium and Ammonium Chlo- 
ride, 137. ; 
Carbonate, 132. 
Chloride, 133. 
Oxide, 134, 136. 
Free from Sulphates, 136. 


INDEX 


Magnesium Sulphate, 136. 
Manganese Chloride, 137. 

Dioxide, 138. 

Peroxide, 138. 

Sulphate, 139. 

Superoxide, 138. 
Manganous Chloride, 137. 

Sulphate, 139. 

Marignac’s Salt, 180. 

Marsh Apparatus. See Preliminary 
Note. 

Mercuric Chloride, 140. 

Oxide, 141. 

Potassium Iodide, 142. 
Mercurous Nitrate, 141. 
Mercury, 140. 

and Potassium Iodide, 142. 

Bichloride, 140. 

Nitrate, 141. 

Oxide, Red and Yellow, 141. 


Metadiaminobenzene Hydrochlo- 
ride, 142. 

Metaphenylenediamine Hydrochlo- 
ride, 142. 


Metaphosphoric Acid, 29. 
Methyl Alcohol, 48. 
Orange, 143. 
Microcosmie Salt, 223. 
Mixture, Kassner’s, 143. 
Mohr’s Salt, 123. 
Molybdic Anhydride, 18. 
Monobasic Calcium Phosphate, 85. 
Monocalcium Phosphate, 85. 


Nitric Acid, 20, 21, 22. See Pre- 
liminary Note. 
Nitrobenzaldehyde, Ortho, 143. 
Nitron, 144. 
Nitrophenol, Ortho, 144. 
Para, 144. 
Nitrosobetanaphthol, 145. 


Orthonitrobenzaldehyde, 143. 
Orthonitrophenol, 144. 





247 


Palladium, 145. 
and Sodium Chloride, 146. 
Chloride, 146. 

Nitrate, 146. 

Palladous Chloride, 146. 
Nitrate, 146. 

Paradiaminodiphenyl, 73. : 

Paranitrophenol, 144. 

Perhydrol, 107. 

Petroleum Ether, 74. 

Phenacetolin, 146. 

Phenolphthalein, 147. 

Phenylhydrazine, 147. 

Phloroglucin, 148. 

Phosphoric Acid, 26, 28, 29. 
Anhydride, 29. 

Phosphorous Pentoxide, 29. 

Piano Wire, 114. 

Platinie Chloride, 149. 

Platinum, 148. 

Chloride, 149. 

Potassium Acetate Solution, 150. 
Acid Pyroantimonate, 151. 
Acid Sulphate, 155. 

Acid Sulphite, 155. 
Acid Tartrate, 156. 
and Cadmium Iodide, 78. - 
and Sodium Tartrate, 184. 
Antimonate, 151. 
Bicarbonate, 151. 
Bichromate, 164. | 
Biniodate, 153. 
Bisulphate, 155. 
Bisulphite, 155. 
Bitartrate, 156. 
Bromate, 158. 
Bromide, 158. 
Carbonate, 159. 

Solution, 161. 
Chlorate, 161. 
Chloride, 162. 
Chromate, 163. 
Chromate, Yellow, 163. 
Cyanide, 164. 


248 


Potassium Dichromate, 164. 
Ferricyanide, 165. ) 
Ferrocyanide, 166. 
Hydrate, 167, 168, 170, 171. 
Hydrosulphide, 183. 
Hydroxide, 167, 

171. 

Purest, 168. 

Purified, 171. 

Purified by 

hol, 170. 

Solutions, 172. 
Iodate, 173. 

Iodide, 173, 175. 

Neutral, 175. 

Nitrate, 175. 

Nitrite, 176. 

Oxalate, Neutral, 177. 

Perchlorate, 178. 

Permanganate, 179, 180. 

Permanganate, Free from Sul- 
phates, 180. 

Stannosulphate, 180. 

Sulphate, 181. 

Sulphide, 181. 

Solution, 181. 
Sulphocyanate, 182. 
Sulphydrate, 183. 
Tetraoxalate, 183. 
Thiocyanate, 182. 

Primary Calcium Phosphate, 85. 

Prussiate of Potash, Red, 165. 

Yellow, 166. 


168, 170, 


Alco- 


Pyrogallol, 185. 
Pyrolusite, 138. 


Red Prussiate of Potash, 165. 
Reduced Iron, 115. 
Residue Unweighable. 

liminary Note. 
Resorcin, 185. 
Resorcinol, 185. 

Blue, 124. 
Rochelle Salt, 184. 


See Pre- 





INDEX 


Schiff’s Reagent, 63. 
Secondary Calcium Phosphate, 84. 
Sodium Phosphate, 217. 
Seignette Salt, 184. 
Silver, 186. 
| Nitrate, 186. 
Nitrite, 187. 
Slaked Lime, 82. 
Soda Lime, 208, 209. 
Sodium, 188. 
Acetate, 189. 
Acid Sulphate, 192. 
Acid Sulphite, 192. 
Amalgam, 189. 
and Ammonium Phosphate, 
223. 
and Potassium Carbonate, 
223. 
Biborate, 193, 194. 
Bicarbonate, 190. 
Bisulphate, 192. 
Bisulphite, 192. 
Borate, 193, 194, 195, 196. 
Purest, Calcined, 195. 
Crystals, 194. 
Fused, 196. 
Bromate, 196. 
Carbonate, 197, 199, 200. 
Anhydrous, 200. 
Crystals, 197. 
Dried, 199. 
Chloride, 200, 201. 
Fused, 201. 
Hydrate, 202, 204, 205. 
Hydroxide, 202, 204, 205. 
from Sodium, 202. 
Purified, 205. 
Purified by Alco- 
hol, 204. 
Solutions, 207. 
‘Solution I, 207. 
Solution II, 207. 
Solution III, 207. 
with Lime, 208, 209. 


INDEX 


Sodium Hydroxide, with Lime, from 
Iceland Spar, 
209. 
Hyposulphite, 221. 
Nitrate, 209. © 
Nitrite, 211, 212. 
Free. from Potassium, 
232. 
Nitroferricyanide, 212. 
Nitroprusside, 212. 
Oxalate, 213. 
Palladous Chloride, 146. 
Peroxide, 215. 
Phosphate, 217. 

Secondary, 217. 
Pyrophosphate, 218. 
Sulphate, 219. 

Sulphide, 219. 
Solution, 220. 
Sulphite Crystals, 221. 
Dried, 221. 
Superoxide, 215. 
Tetraborate, 193, 194. 
Thiosulphate, 221. 
Tungstate, 222. 
Wolframate, 222. 
Solution Ammonium Citrate, 55. 
Dithiocarbo- 
nate, 56. 
Sulphide, 62. 
Sulphydrate, 
62 
Thioacetate, 
63. 
Barium Hydroxide, 71. 
Cadmium Borotungstate, 78. 
Calcium Hydroxide, 131. 
Caustic Soda, 207. 
Ferric Chloride, 119. 
Hydrogen Peroxide, 107. 
Iron Chloride, Ferric, 119. 
Lead Subacetate, 130. 
Potassium Acetate, 150. 
Carbonate, 161. 





249 


Solution Potassium Hydroxide, 172. 
Sulphide, 181. 
Sodium Hydroxide I, 207. 
Hydroxide II, 207. 
Hydroxide III, 207. 
Sulphide, 220. 
Stannous Chloride, 226. 
Zine Iodide-Starch, 234. 
Sérensen’s Oxalate, 213. 
Specific Gravities. See Preliminary 
Note. 
Stannous Chloride, 225. 
Sulphurated Lime, 87. 
Sulphuric Acid, 34, 36, 37. 
Anhydride, 37. 
Sulphur Trioxide, 37.. 
Synthetic Indigo, 110. 


Tables, 238, 239, 240, 241. 
of Atomic Weights, 238. 
of Equivalents, 238, 239, 240, 
241. 
of Logarithms, 238, 239, 240, 
241. 
Tannin, 42. 
Tertiary Calcium Phosphate, 86. 
Tetraiodofluorescein, 112. 
Thymol, 224. 
Tin, 224. 
Chloride, 225. 
Solution, 226. 
Tribasic Calcium Phosphate, 86. 
Tricalcium Phosphate, 86. 
Trinitrophenol, 31. 
Unweighable Residue. See Pre- 
liminary Note. 
Uranium Acetate, Free from So- 
dium, 227. 
Nitrate, 228. 
Uranyl Acetate, 227. 
Nitrate, 228. 


Vegetable Indigo, 111. 


250 INDEX 





Water, Ammonia, 50, 51, 52. See | Xylidine, 230. 
Preliminary Note. 
10 per cent, 52. Yellow Potassium Chromate, 163. 
20 per cent, 51. Prussiate of Potash, 166. 
28 per cent, 50. 
Concentrated 51. Zine, 230, 231, 232. 
Stronger, 50. Chloride, 234. 
Baryta, 71. Dust, 232. 
Bromine, 77. Free from Arsenic, 232. 
Chlorine, 90. Free from Arsenic, Sulphur, 
Distilled, 229. Phosphorus, and Iron, 230. 
Hydrogen Sulphide, 109. Free from Arsenic, nearly Free 
Iodine, 114. From Iron, 231. 
Lime, 131. Iodide-Starch Solution, 234. 
Stronger Ammonia, 50. Oxide, 235. 
Weights Atomic, 238. See Pre- Sulphate, 236. 
liminary Note. 





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